User Manual for ST models including: WBC86TX Qi Compatible Wireless Power Transmitter, WBC86TX, Qi Compatible Wireless Power Transmitter, Wireless Power Transmitter, Power Transmitter, Transmitter
STEVAL-WBC86TX - Qi-compatible wireless power transmitter evaluation board for 5 W application based on STWBC86 - STMicroelectronics
STEVAL-WBC86TX wireless power transmitter evaluation board for up to 5 W Qi-BPP applications - User manual
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DocumentDocumentUM3161
User manual
Getting started with the STEVAL-WBC86TX wireless power transmitter evaluation board for up to 5 W Qi-BPP applications
Introduction
The STEVAL-WBC86TX evaluation board, based on the STWBC86, is designed for wireless power transmitter applications and allows its users to quickly start their 5 W Qi BPP wireless charging projects. The STWBC86 wireless transmitter IC can deliver up to 15 W (coil dependent), however this reference design document is limited to only provide sufficient information to develop a project for up to 5 W charging compatible with Qi 1.2.4 Baseline Power Profile (BPP) power transfer by Wireless Power Consortium's inductive wireless power technology. The integrated circuit requires only a few external components and can work with 5-20 V input voltage. Using an on-board USB-to-I2C bridge, the user can monitor and control the STWBC86 using the STSW-WPSTUDIO graphical user interface (GUI). The STEVAL-WBC86TX includes several safety mechanisms providing overtemperature (OTP), overcurrent (OCP), and overvoltage (OVP) protections as well as foreign object detection (FOD) for reliable designs.
Figure 1. STEVAL-WBC86TX board
To get started with the STEVAL-WBC86TX, the following items are needed to use the reference design kit:
· Evaluation kit components: STEVAL-WBC86TX board
UM3161 - Rev 1 - July 2023 For further information contact your local STMicroelectronics sales office.
www.st.com
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· Additional hardware: USB adapter 5 V / 3 A or power supply 2 x USB Type-C® cables (one can be replaced with either 2.1 mm jack or pin cable) Windows PC
· Software: STSW-WPSTUDIO Wireless Power Studio PC GUI installation package I2C drivers
· Application notes: GUI guide: UM3164
Begin by installing both the I2C drivers and the STSW-WPSTUDIO GUI. Visit the ST website for additional information regarding the STSW-WPSTUDIO GUI. Connect a 5 V power supply to power the board using either the USB Type-C®, jack, or pin cable. Using a jumper, select the chosen method of power delivery on header P1. Using a USB Type-C® cable, connect the board to the PC (connector P4 on the board). This allows the user to communicate with the board - program it and monitor its function.
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Reference design specifications
1
Reference design specifications
The target specifications of the STEVAL-WBC86TX evaluation board are as follows:
Table 1. STEVAL-WBC86TX target specifications
Parameter Qi compatibility Tx application PCB area
Tx coil specifications
Qi Tx topology Input voltage (Vin) Input current (Iin)
Host MCU
USB-to-I2C converter
Efficiency
Applicable charging gap between Tx and Rx coils (z-distance) Operational modes
Description Qi 1.2.4 compatible 40 mm x 24 mm Inductance 6.3 uH, DCR 20 mOhm, ACR 20 mOhm @ 100 kHz, dimensions 53.3 mm x 53.3 mm x 6 mm A11a 5 V 1.5 A STM32 used as a reference, the reference I2C driver can be ported to any other MCU family FT260, embedded in the evaluation board 77.6 % (5 W operation) with STEVAL-WLC38RX 81 % (peak efficiency) with STEVAL-WLC38RX at 3 W
3 13 mm (5 W output) with STEVAL-WLC38RX receiver, maximum 16 mm stable communication without output enabled
Transmitter only
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Overview of the board
2
Overview of the board
The STEVAL-WBC86TX evaluation board is optimized for performance. The board features:
·
STWBC86 wireless power transmitter chip with BPP 1.2.4 compatible firmware
·
Very few external components, optimized BOM and PCB space
·
On-chip high efficiency full bridge inverter
·
32-bit, 64 MHz Arm® Cortex® microcontroller with 8 KB SRAM
·
9-channel, 10-bit A/D converter
·
On-chip thermal management and protections
·
Foreign object detection (FOD) function
·
I2C interface for communication with host system (optional)
·
On-board USB-to-I2C converter
·
Chip scale package (CSP), ROHS complaint
Figure 2. STEVAL-WBC86TX evaluation board features
·
Series resonant capacitors (Ctank) and the transmitting coil form a resonant circuit. This circuit is in charge
of transmitting the power signal, so any components/tracks involved should be rated accordingly.
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Test points
·
CBT1 and CBT2 are bootstrapping capacitors, which ensure the proper functionality of the integrated
inverter. This should be considered during PCB design, as these nets generate noise and should therefore
be routed separately from sensitive circuits.
·
ASK demodulation circuit - apart from transferring power, the power signal is also used for receiver to
transmitter communication. The communication signal is extracted from the power signal using the ASK
demodulation circuit and fed into the VS pin of STWBC86 for processing. For further details, refer to
Section 4.12.1 ASK communication.
·
USB/I2C converter - provides a communication channel between a PC and STWBC86. LED D6 (red)
indicates the I2C converter is powered, D4 (yellow) indicates that STWBC86 is connected to the GUI. LED
D5 (green) indicates the I2C communication was initialized and is ready. Switch S1 resets the converter.
Please note that header P2 connects the converter's I2C signals to the STWBC86 I2C signals. Short the
corresponding pins with a jumper to establish a connection between the two ICs.
·
Power input (USB Type-C® connector/jack/pin header) - 3 separate inputs can be used to power the board,
but only one is used at a time. Therefore, it is necessary to select the input using a jumper on header P1.
·
Red LED (D3) - connected to GPIO0, can be configured to signal various conditions (power ready,
communication active etc.).
2.1
Test points
The STEVAL-WBC86TX features several connectors and test points to provide easy access to key signals.
Figure 3. Connectors and test points
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Basic operating modes
Connector / test point VIN VINV P2 P14 TP1 TP2 TP3 TP4 TP5 TP6 TP7 TP8
Table 2. Connectors and test points
Name VIN VINV I2C Digital interface Ring node VIN AC2 AC1 VINV V1V8 GND VS
Description Input voltage (power pins) Inverter voltage pins SDA, SCL, INT, and RST signals for I2C communication I2C, GPIO, and RST signals Ring node STWBC86 input voltage sensing Resonant circuit terminal Resonant circuit terminal STWBC86 inverter voltage sensing STWBC86's 1.8 V LDO output Ground VS signal sensing
2.2
Basic operating modes
The STWBC86 is designed to work in transmitter mode only. Once the board is powered up, the device automatically starts pinging (if enabled), which means it starts scanning its power transfer interface for a potential power receiver. Once a suitable receiver is found, the STWBC86 initializes power transfer. After the receiver is removed from the interface, the device returns to the pinging phase.
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Graphical user interface (GUI)
3
Graphical user interface (GUI)
The STWBC86 (and other STMicroelectronics wireless charging devices) can be configured using STMicroelectronics' STCHARGE Wireless Power Studio GUI. The GUI can also be used to control, monitor, and program the device.
For more information, please see the UM3164.
3.1
Connecting STWBC86 to PC GUI
Connect the board to a PC by plugging a USB Type-C® cable into the connector J3. Make sure the STWBC86 I2C pins are connected to the USB Type-C® connector. This can be done by shorting the appropriate signals (SDA, SCL, INT) on header P2. Power up the board and open the GUI on your PC. Click the Connection button in the top menu.
Up to two devices can be connected at a time - this allows the user to control both Rx and Tx at the same time). Select WBC86 as the Tx and click the Connect button on the right side of the window.
Figure 4. GUI connection
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Figure 5. GUI device connection
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Patch and Configuration files
3.2
Patch and Configuration files
Firmware of the device can be updated using a Patch file (a binary file in .memh format). The latest version of the Patch can be found on this [ST website]. Updating the firmware is not required but may improve performance of the board.
The device can be configured using a Configuration file, a binary file containing settings of all registers, which can be found in the GUI. The GUI can also be used to generate a custom Configuration file, making it easier to quickly change configuration of the board and/or transfer the configuration to another board.
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Configuration file generation
3.3
Configuration file generation
Using the STSW-WPSTUDIO makes generating the Configuration file quite simple the user can do so by clicking the "Save TX" button in the TX Registers tab or the Common Registers tab, entering a configuration ID number (used for version control) and pressing OK. The GUI then asks for a save destination. After choosing a location, the Configuration is saved as a .memh file in the selected folder.
Figure 6. Generation of configuration file
Figure 7. Version of the configuration file
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Figure 8. Saving of the configuration file
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Header file
3.4
Header file
The GUI can also be used to generate a Header file, a binary .h file containing both Configuration and Patch files. The Header file makes programming the device using a host IC easier, as both Configuration and Patch can be loaded at once by simply including the Header file in the host code.
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Header file generation
3.5
Header file generation
A custom Header file can be generated in the Header Generator tab. Start by selecting WBC86 in the top menu.
Figure 9. Header generator - chip selection
Continue by selecting the Patch and Configuration file and press Generate. A pop-up window appears, asking to confirm the correct Patch version has been selected.
Figure 10. Header generation - pop up window
After confirming the Patch version, the GUI asks for a save destination. After choosing a location, the Header file is saved as a .h file in the selected folder.
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Figure 11. Header generation - save header file
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Header file generation
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Programming the device
3.6
Programming the device
The device can be programmed in three ways by changing the register values directly in the GUI, by using a Header file, which loads both Configuration and Patch files at once, or by loading the two memh files separately using the GUI.
The Configuration and Patch files directly modify values stored in the NVM. Therefore, any changes written by Configuration and Patch files will be retained even after reset. On the contrary, changes made by the GUI (Write Tx button) are written into the I2C registers, which are cleared upon reset.
To load the Header file using the GUI, navigate to the Programming tab in the side menu. Select WBC86 in the top menu and "HEADER" in the toggle selector.
Figure 12. Programming the device by header file
Select the .h file that is to be written. The GUI automatically identifies the Patch and Configuration files included in the Header file. Press the "Write" button to load the Header file into the device.
To load the memh files (Patch and Configuration) using the GUI, navigate to the Programming tab in the side menu. Select WBC86 in the top menu and "MEMH" in the toggle selector.
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Programming the device Figure 13. Generating the header file by patch and configuration files
Select Patch and Configuration files that are to be written. Press the "Write" button to load the .memh files into the device.
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4
Device description and operation
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Device description and operation
4.1
System block diagram
Figure 14. System block diagram
4.2
Integrated power inverter
The integrated power inverter is a key block in charge of converting the DC input into an AC power signal for the transmitting coil. The power inverter consists of four N-channel MOSFET transistors arranged into a H-bridge, conveniently driven by an internal control block, which also simultaneously monitors the key parameters of the board to optimize switching and charging the external bootstrap capacitors for the high-side switches.
Some applications may require driving the power inverter in half-bridge mode for example delivering a very small amount of power might be difficult with some Tx/Rx coil combinations. The STWBC86 can be configured to operate in half-bridge mode using the GUI.
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Figure 15. H-bridge mode settings
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ADC
4.3
ADC
The STWBC86 allows the user to monitor key operational parameters using an internal ADC. Instantaneous values can be displayed in the Charts tab of the GUI. The GUI enables the user to monitor the input voltage, input current, device temperature, operating frequency, duty cycle, transmitted power, and more.
Figure 16. GUI charts monitoring
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4.4 4.5
4.6 4.7 4.8
4.8.1
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LDOs
LDOs
The device is equipped with 2 internal low dropout regulators (LDOs) a 5 V and a 1.8 V one, with the latter deriving its power from the former.
The 1.8 V LDO powers the digital part of the IC, while the 5 V LDO powers the analog part of the IC but can also be used to power external low-power circuitry (such as LEDs). The maximum current externally drawn from this LDO should not exceed 10 mA.
External LDO capacitors should be placed as close to the IC as possible.
Power-up sequence
Once power is applied to the input (and the device is not forced into reset), the power-up sequence of the device starts. After the internal main LDO reaches the target output voltage, the digital core of the device starts operating. Default device settings are used until the digital core is woken up after which the firmware loads settings saved in the Configuration file.
If both Patch and Configuration files are loaded into the device and the automatic start function is enabled, the device enters the digital ping phase of power transfer (see Section 4.11 WPC Qi wireless power transfer). If the automatic start function is disabled, the device does not proceed to the ping phase until the TX_EN command is executed.
If Patch and/or Configuration files are not loaded, the device stays in a so-called DC mode. In this mode, the device is powered up and ready to be programmed. The device also enters this mode if either the Patch or Configuration, or both files, are corrupt.
UVLO
The STWBC86 is also equipped with a UVLO function. The UVLO is triggered when the input voltage drops below 2.9 V. The inverter stops switching and the device is powered down. Normal operation is resumed as soon as the input voltage rises above 3 V.
Chip reset
The device can be forced into reset by pulling the RSTB pin to ground. This can easily be done by a jumper on header P14. When the RSTB pin is released and allowed to be pulled up, the device resumes normal operation.
Protections overview
The STEVAL-WBC86TX board uses both hardware and software protection to ensure safe voltage and current levels. The purpose of those protections is to avoid damage to either the board itself or even the potential receiver, caused by unexpected conditions overvoltage and/or overcurrent. The temperature is also monitored, although only software protection is used for this purpose.
The software protections can be enabled/disabled in the GUI; the GUI can also be used to adjust thresholds for the respective protections.
The hardware protections are permanently set and cannot be disabled or adjusted in the GUI. The thresholds for the hardware protections are as follows:
·
Overcurrent protection: 3 A (fuse)
·
Overvoltage protection: 22 V (TVS diode)
The triggering of a software protection results in the transmitter terminating a power transfer and generating a corresponding interrupt (can be configured in the GUI).
Overcurrent protection (OCP)
A transmitter overload or a short on the output (transmitting coil) may lead to excessive input current values. To prevent damage to the transmitter caused by such currents, two separate protections (hardware and software) are implemented.
A fuse (F1) on the input track rated at 3 A serves as the hardware protection, while an ADC monitoring the input current serves as the software one. If the input current exceeds a set threshold, the power transmitter terminates the power transfer and generates an OCP interrupt. The threshold is configurable in the GUI and can be set in a range of 0 to 2500 mA.
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Figure 17. OCP settings
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Protections overview
4.8.2
Overvoltage protection (OVP) Excessive input voltage may damage the board and/or device. For this reason, a TVS diode is placed at the input of the board. The IC is also equipped with an ADC dedicated to monitoring the input voltage level. The protection can be enabled/disabled in the GUI and the threshold can be set in a range of 0 to 25.5 V. Triggering OVP also leads to power transfer termination, as an increase in transmitter input voltage may also lead to an increased Rx VRECT voltage.
Figure 18. OVP settings
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4.8.3
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Protections overview
Overtemperature protection (OVTP) The temperature of the IC is continuously monitored by a temperature sensor. Excessive IC temperature may indicate that either the operating power is too high, or an internal fault occurred. It should be considered that PCB design may affect thermal performance as well. If the temperature exceeds a set threshold, power transfer is terminated, and an OVTP interrupt is generated by the transmitter. The threshold is configurable in the GUI and can be set in a range of 0 to 151 °C.
Figure 19. OVTP settings
4.8.4
NTC
An external NTC can be used to further monitor the operational temperature of the board. The user may choose a component/board region to be monitored by placing the NTC on it/nearby, although monitoring the transmitting coil is presumably the most common practice.
Together with a pull-up resistor, the NTC forms a voltage divider, which is connected to the STWBC86 NTC pin. The NTC pin is 1.98 V tolerant, although an internal ADC supports only up to 1.5 V NTC voltage reading. Therefore, it is recommended to design the voltage divider to reach the (low) NTC threshold at the highest allowed temperature, while leaving a large enough margin for accurate temperature monitoring (the NTC voltage should be kept below 1.5 V).
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Figure 20. NTC connection on board
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Protections overview
The user can choose if triggering this protection only generates a corresponding interrupt, or if the device also terminates the power transfer upon triggering. The interrupt must be enabled when power transfer termination is desired. To set the NTC threshold using GUI, the threshold value must be set (in mV) based on the parameters of the resistor divider. The protection will be triggered when the divider output voltage drops below the set threshold.
Figure 21. NTC settings
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4.9
4.9.1
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Foreign object detection (FOD)
Foreign object detection (FOD)
A foreign object is any object placed either on or near the transmitting coil, which is not considered a valid wireless power receiver and is magnetically active. Presence of the magnetic field generated by the transmitting coil may cause eddy currents to form in the foreign object (such as coins, keys etc.), which in turn would heat the object to potentially dangerous temperatures. To avoid possible damage to the device or even injury to the user, the power transmitter must be able to detect the presence of a foreign object. This detection can be implemented in several different ways. One of the most common ways is estimating the amount of power lost in the system. The power receiver indicates the total amount of received power from the power transmitter. This power consists of power available to the load and power loss, which occurs on the supporting circuitry. A high power loss value could indicate the presence of a foreign object. The STWBC86 uses precise AD converters and 32-bit arithmetic to monitor input power and can therefore estimate the amount of power lost beyond the power transmission interface using a mathematical model of the system.
FOD tuning The default FOD parameters are optimized for STEVAL-STWBC86TX. Any change to the topology might require adjustments to the FOD parameters too. The user can record these parameters using the GUI to properly trigger FOD when required, as well as avoid false triggers. The most common use conditions include: 1. Aligned position without any FO. 2. Misaligned position without any FO. Parameters should be recorded in a few various misalignments,
including the maximum expected one - usually 5mm misalignment in all x, y, and z axis respectively (excluding their combinations). 3. Aligned position with FO - reference foreign objects prescribed by the Qi specification, coins, keys etc. Each FO requires a separate measurement. 4. Misaligned position with FO. The FOD parameters should be recorded for the whole range of Rx loads. Before the actual tuning, please disable the EPT FOD function of STWBC86TX in the TX registers tab. Leaving the function enabled would result in termination of the power transfer during parameter logging, caused by the presence of FO. However, for the change to take an effect, you will have to generate and load a new CFG file with the feature disabled, as this setting cannot be changed while the device is running.
Figure 22. Disable FO detection
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Foreign object detection (FOD)
Data collection To collect accurate data, the ring node voltage divider must be set accordingly, please refer to chapter 6.2 Ring node voltage sensing for more information. To start the tuning process, head to the TX FOD tuning tab of the GUI. To add a new data set, press the '+' button on the right side of the screen. The data set can be labelled using the name line below to help better distinguish it later.
Figure 23. Add a new dataset
Ticking the check box next to a data set will toggle its display it in the plot on the next page of the tool. If you want to hide a particular data set, simply untick the corresponding check box.
Figure 24. Display dataset in plot
The newest data is always added to the bottom of the set. When enabled, the Auto Scroll function will automatically take you to the end of the list after logging a new set.
Figure 25. Enable auto scroll
Additional options can be found by clicking the '...' button next to the Auto scroll box.
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Figure 26. Additional dataset options
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Foreign object detection (FOD)
The first button in the drop-down menu will sort the captured data by input current. Always sort the data after the capturing is finished. Otherwise, the load curve might not display correctly on the second page of the tool. The second button will delete all data. The third will enable you to save the data in a .txt file format and the last lets you import any previously captured data. The loaded data will be appended to the end of the list. Click the '...' button next to any data set to access its properties. Here, you can adjust the line style used in the plot and the display colour for the data set. A solid line is used by default for each data set but can be switched to a dashed line by ticking the line style box. This can be used to distinguish different conditions, such as sets with and without a foreign object.
Figure 27. Line properties - dashed/solid
Figure 28. Line properties - color
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Foreign object detection (FOD)
Before capturing a new set of data, prepare the intended operating conditions (FO, misalignment) and allow power transfer to be established, then click the start button. The GUI will then begin to periodically log the operating conditions and the logged data will be shown in a table in the middle of the GUI window. We recommend recording data for the whole load range in appropriate steps. It is also recommended to record at least three data points for each load, as the operating parameters may vary slightly mostly because of noise.
Figure 29. Logged data
One of the variables used to estimate foreign object presence is received power, reported by the RX via received power packet (labelled RxPwr in the table). This packet is usually only sent once every 1500 ms. It is therefore necessary to wait for about 1.5 seconds after changing the load to allow the RPP value to be updated before reading. We recommend using the following procedure:
1. Record a few samples on the first load step.
2. Pause the recording, change the load and wait at least 1.5 s.
3. Optional: check if the recorded samples are all acceptable.
4. Resume the recording.
5. Repeat until enough load steps are recorded.
Data points containing the old RPP value can be distinguished by comparing both the RxPwr and Icur values to the previous points. If a sample contains an RPP value similar to a previous point (load step), but the current is significantly different, it is most likely caused by desynchronization of the current and the received power reading. The desynchronized data points can also be spotted in the plot, as those points will usually be significantly higher/ lower than the rest.
Any unsuitable data point can be deleted using the "X" button in the Action column.
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Figure 30. Delete a single data point
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Foreign object detection (FOD)
Figure 31. Spot wrong data point in plot
Parameter tuning
Plot of the logged data can be seen on the second page of the tuning tool, accessed by clicking the "2" button in the upper part of the window. Here you can see estimated power loss curves based on the data captured.
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Figure 32. Plot logged data
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Foreign object detection (FOD)
The logged data are processed before being plotted, as the tool also takes into consideration a few physical properties of the circuit. Those properties are set in the top part of the parameter list on the right side of the window and include:
·
TxSwitchLossCoef selects if the switch loss should be included in the calculation.
·
CoilResistance refers to the STWBC86TX coil resistance.
·
Cser and CserResistance refer to the STWBC86TX series resonant capacitor capacitance and resistance
values.
Values listed below are the tuneable parameters of the FOD algorithm.
VcpPeakDrop is a ring node voltage value modifier. CoilCoef is a scaling factor, which incorporates frequency dependent losses into the calculation. Adjust the VcpPeakDrop and CoilCoef values until the foreign object and non-foreign object curves are as separate as possible. VcpPeakDrop can be set in steps of 50 mV, CoilCoef can be set in steps of 1.
PlossThreshold sets a threshold for foreign object detection. If the calculated power loss is higher than the set threshold, FOD protection is triggered. PlossThreshold can be set in steps of 32 mW.
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Figure 33. Ploss threshold
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Foreign object detection (FOD)
After adjusting all previously mentioned parameters, the curves can be further adjusted by setting power loss offsets for selected input current intervals. Begin by defining the intervals using the CTC values. Those values refer to the respective input current thresholds and are displayed as vertical lines in the plot. A unique offset can be applied to every interval using the corresponding OLC slider. Please note that the first OLC value corresponds to the interval ranging from zero input current to CTC [1], the second corresponds to interval "CTC [1] to CTC [2]", and so on, with the last OLC value corresponding to interval "CTC [8] and above". Remember, that the offsets adjust the relative position of ALL curves to the PlossThreshold, they cannot be used to separate the FO and non-FO curves. Only VcpPeakDrop and CoilCoef can be used to separate the curves.
Figure 34. CTC threshold
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Foreign object detection (FOD)
The goal of FOD tuning is to establish a threshold which would both trigger FOD when foreign object is present and not trigger FOD when not. This would translate to a condition when all FO curves are above the set threshold and non-FO curves are below the threshold, with a sufficient margin (at least for the non-FO curves). The margin is necessary to ensure the power transfer in not terminated, even when there is a slight misalignment of the coils. Under some condition, the power dissipated in the foreign object might be very low, which would cause the FO and non-FO curves to be very close to each other. This would make it almost impossible to separate the curves (and to detect the presence of foreign object) effectively. However, the main reason of FOD is preventing excessive heating of the FO. A low power dissipation would lead to only a minor temperature rise of the FO. Certain value combinations may not be suitable. To help you avoid problems during operation, non-recommended coil coefficient, VcpPeakDrop and OLC values will be highlighted in red. Saving and uploading those values may cause false FO detection during operation.
Figure 35. Unsutiable parameter values highlighted in red
Parameter loading
The new FOD parameters must be loaded into the chip when the tuning is finished. However, before loading the parameters, please remember to enable the EPT FOD function, you have disabled as per the instructions at the beginning of this guide.
To load the parameters into the device, begin by saving the parameters using the "Write TX" button. Continue by navigating to the TX Registers, Tx FOD Configuration and enable FOD. Optionally, adjust the FOD debounce value. Click the "Save TX" button to generate a new CFG file containing the new parameters. Finish by loading the CFG file into the device using the standard procedure described in section 3.6.
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Figure 36. Load tuned parameters
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Foreign object detection (FOD)
Figure 37. Enable FOD and set FOD debounce
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4.10
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EPT reason
EPT reason
Power transfer may be terminated for several different reasons. Determining the exact cause might be difficult, as more than one fault condition might have been met. For this reason, the power transmitter is equipped with EPT reason registers. Those registers indicate the state of various parameters, which might be responsible for the termination. It should be noted that, as mentioned above, multiple bits (reasons) might be set to one after a power transfer termination occurs.
Figure 38. EPT reason
The power receiver may generate an EPT request as well and send it to the transmitter. If the transmitter receives an EPT packet from the receiver, it terminates the power transfer immediately. The EPT packet that the receiver sends should also contain the reason for the request. The reason can be retrieved from the communication and decoded by the user/host. Contents of the packet can be found in the buffer (MSG RECV1&2), which can be found in the communication section of the Common Registers tab.
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Figure 39. Received message
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EPT reason
However, the values in the buffer are updated frequently, therefore reading the RX EPT reason requires using a host controller triggered to an RX EPT packet interrupt.
Figure 40. EPT interrupt setting
The GUI enables the user to set a debounce value for EPT conditions. This means that the device does not terminate the power transfer immediately upon registering an EPT condition, but rather after registering a number of conditions greater than the specified value. As an example: when the debounce is set to 2 and the device temperature exceeds the set overtemperature threshold, the device terminates power transfer only after 3 consecutive temperature measurements exceed the threshold.
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WPC Qi wireless power transfer
Figure 41. Protection debounce setting
The GUI enables the user to select which (EPT) condition causes the transmitter to stop pinging even after the EPT condition no longer applies. When used, this feature keeps the device inactive until it is restarted (by a power cycle) by the user. In addition, entering the inactive state can be indicated by assigning a TX error (0x1E) function to one of the GPIO pins (see Section 4.14 GPIOx and INTB pins).
Figure 42. EPT reping settings
4.11
Checking a box causes the corresponding condition to block the device from pinging after it is triggered.
WPC Qi wireless power transfer
The flowchart in the figure below shows the steps required to reach power transfer in the Baseline Power Profile (BPP) according to Qi 1.2.4.
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Bidirectional communication
Figure 43. Power transfer start up sequence
4.11.1
4.12
Note:
For more details refer to: The Qi Wireless Power Transfer System Power Class 0 Specification, Parts 1 and 2: Interface Definitions, Version 1.2.4 February 2018.
·
Digital ping: this phase is an interrogation session during which the potential power receiver is expected to
reply through amplitude shift-keying (ASK) modulation as defined by the Qi specification. After a valid
power receiver is detected, the transmitter proceeds to the Identification & Configuration phase.
·
Identification & Configuration: this phase aims to identify the receiver and to gather information necessary
for a stable and reliable power transfer, such as the maximum power or FSK communication parameters.
After receiving the information, the power transmitter creates a Power transfer contract; basically a
summary of the operational parameters. After the power receiver is identified and the power transfer is
created, the power transmitter proceeds to the power transfer itself.
·
Power Transfer: this is the final step. The power transmitter initially increases and subsequently modulates
the transmitted power in response to control (feedback) data from the receiver. The receiver periodically
sends information to the power transmitter, such as required power (CEP), received power (RPP), etc.,
which are used to maintain a closed control loop. If a critical event (for example, overvoltage, overcurrent
or overtemperature) occurs, the power transmitter terminates the power transfer immediately.
Wireless power interface
Wireless power interface is the area in which power transfer takes place. It consists of two parts the transmitter (primary) power interface and the receiver (secondary) power interface. The main component of the interfaces is the transmitting/receiving coil. The user should avoid placing any objects which are magnetically active, yet are not required for the power transfer itself, on or near the wireless power interface in order to avoid possible damage or injury (see Section 4.9 Foreign object detection (FOD)).
Detection of a valid receiver on the primary wireless power interface is performed by a digital ping. A digital ping is a burst of power generated by the transmitter; its parameters are defined by the Qi specification. The target of this burst is to generate enough power for the receiver to establish communication between the transmitter and the receiver.
The Qi specification defines a specific way that the receiver is expected to answer the digital ping. The reason is that only a proper answer can inform the transmitter that a valid power receiver was placed on the wireless power interface.
Bidirectional communication
The amount of power transmitted is (from a control standpoint) fully dependent on the operating conditions of the power transmitter (that is, its bridge voltage, operating frequency and duty cycle).
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UM3161
Bidirectional communication
Since there is no direct electrical feedback from the load (system output) to the power transmitter, the power receiver must establish communication with the power transmitter to provide this feedback instead. To match load requirements and prevent excessive power transmission, the power receiver communicates to the power transmitter the required power level using amplitude shift keying (ASK). This is done by the receiver modulating the amount of power that it draws from the power signal. The transmitter detects this as a modulation of the voltage across and/or current through the transmitting coil and adjusts its operating conditions accordingly. The power transmitter can communicate to the receiver as well, this time using frequency shift keying (FSK). This is done by the power transmitter directly modulating the power signal. Communication in this direction enables proprietary communication. STWBC86 supports proprietary packet FSK reply on proprietary ASK packets from Rx. This feature is requiring control from the external host MCU on Tx side and details can be found in dedicated Application Note about bidirectional communication between STWLC38 and STWBC86.
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4.12.1
UM3161
Bidirectional communication
ASK communication
A state (either high or low) is characterized by the amplitude being constant (with a certain variation ) for at least 150 ms.
If the power receiver and the power transmitter coils are properly aligned, then for all appropriate loads at least one of the following three conditions apply.
·
The difference of the amplitude of the transmitter coil current in the high and low state is at least 15 mA
·
The difference of the amplitude of the transmitter coil voltage in the high and low state is at least 200 mV
·
The difference of the transmitter coil current in the high and low state is at least 15 mA. The transmitter coil
current is measured at instants in time that correspond to one quarter of the cycle of the control signal
driving the half-bridge inverter
Figure 44. Amplitude modulation of the Power Signal
Note:
For more details refer to: The Qi Wireless Power Transfer System Power Class 0 Specification, Parts 1 and 2: Interface Definitions, Version 1.2.4 February 2018.
The power receiver uses a differential bi-phase encoding scheme to modulate the data bits onto the power signal. The power signal is then demodulated by the power transmitter's external demodulation circuit and the demodulated signal is fed into the VS pin of STWBC86 for processing.
The communication itself is carried out via packets. Each packet consists of 4 parts and each of those parts consists of several bits/bytes.
Each communication bit is synchronized to the power receiver's internal 2 kHz clock signal period. A ONE bit is encoded as two transitions of the power signal, while a ZERO bit is encoded as a single transition.
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Bidirectional communication Figure 45. Example of a differential bi-phase encoding scheme
To transmit a single byte of data, the power receiver must send an 11-bit sequence. This sequence consists of a START bit (ZERO), the 8 data bits of the byte (LSB first), a parity bit and a STOP bit (ONE). The parity is odd, meaning an even number of ONE bits in the data byte results in the parity bit being equal to ONE, while an odd number of ONE bits in the data byte results in the parity bit being equal to ZERO. An example of such message can be seen in the image below:
Figure 46. Example of the asynchronous serial format
A packet consists of a preamble, header, message, and checksum. The preamble contains 11 to 25 ONE bits and enables the power transmitter to synchronize with the incoming data. The header, message, and checksum are sequences of three or more bytes. The header indicates the packet type while also implicitly providing the size of the message. The checksum consists of a single byte. It is calculated as an exclusive-OR of both the header and message bytes and enables the power transmitter to check for transmission errors. For a more detailed explanation please refer to the Qi Specification, section Power Receiver to Power Transmitter communications interface.
Figure 47. ASK communication example - high load current
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Figure 48. ASK communication - no load
UM3161
Bidirectional communication
4.12.2
FSK communication The power transmitter modulates the power signal by switching between its normal operating frequency fop and its modulated frequency fmod. The difference between fop and fmod can be described by two parameters: polarity and depth. Polarity is given by the difference between fmod and fop a positive polarity corresponds to a positive difference, while a negative polarity corresponds to a negative difference.
Depth describes the magnitude of difference between fop and fmod. Please note that a negative polarity results in a higher induced voltage on the power receiver coil and should therefore be used with care.
The FSK communication is executed via packets. Each packet consists of 3 parts a header, a message, and a checksum. The header is a single byte that indicates the packet type, while also implicitly providing the size of the message part. The message size can range from 1 up to 27 bytes. The checksum is a single byte which provides a way to check for transmission errors. It is calculated as an exclusive-OR of the header bytes and the message bytes.
Each FSK bit is aligned to 512 periods of the power signal. A ONE bit is represented by two transitions over the 512-period slot - the frequency change occurs at the very start of the slot and after 256 power signal periods pass. A ZERO bit is represented by a single transition (at the start of the 512-period slot).
Figure 49. Example of differential bi-phase encoding
Each data byte is transferred as a sequence of 11-bits. The sequence consists of a start bit (ZERO), the data byte itself, a parity bit, and a stop bit (ONE). The parity used for byte encoding is even the parity bit set to a ONE if the data byte contains an odd number of ONE bits. If the data byte contains an even number of ONE bits, the parity bit is set to a ZERO instead. This encoding scheme is used for all 3 parts of the FSK packet - the header, message, and checksum.
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Bidirectional communication
There is also an additional type of message that can be sent from the transmitter to the receiver a response to a receiver's message. A response consists of 8 bits, so the receiver can use quite a simple logic to decode it. The response can be either Acknowledge (ACK), Not-Acknowledge (NACK) or Not-Defined (ND). ACK is encoded as a series of 8 ONE bits, NACK is encoded as 8 zero bits and ND is encoded as a series of 8 bits of alternating ZERO and ONE bits (`01010101').
Figure 50. Format of the three defined responses
4.12.3
For a more detailed explanation please refer to the Qi Specification, section Power Transmitter to Power Receiver communications interface.
Most common Qi communication packets
·
Control error packet (CEP) provides feedback from the power receiver to the power transmitter about the
amount of power required by the load. CEP is a two's complement signed integer; its maximum range is
-128 to +127. Its value is calculated by the receiver as a portion of the currently transmitted power, by
which the current power level should be increased/decreased. A negative CEP indicates less power is
required, while a positive CEP indicates more power is required. CEP equal to zero indicates no changes
of the operation point are required.
·
Received power packet (RPP) value is calculated by the power receiver as a portion of the maximum
power value contained in the configuration packet and is used to inform the transmitter about the amount of
power received by the receiver. This information is mainly used for foreign object detection.
·
Signal strength packet (SS) indicates the degree of coupling between the transmitting and receiving coils.
Its value is an unsigned integer, and it is calculated from the current power/voltage level as a portion of the
maximum expected power/voltage.
·
End power transfer (EPT) packet is generated by the receiver, and its purpose is to signal to the
transmitter that power transfer shall be terminated. This request may have several causes, but the most
common ones are:
The battery is fully charged,
A protection was triggered (overvoltage, overtemperature, etc.),
An internal fault in the receiver occurred,
No/insufficient response to control error packets is detected.
·
Proprietary packet (PP) enables sending custom messages between the transmitter and the receiver. Qi
standard defines different proprietary packet types, which can range in length from 1 to 20 bytes.
·
Charge status packet (CSP) contains an unsigned integer which states the current charge status of the
battery in the receiving device. CSP equal to 100 means the battery is fully charged, while CSP equal to 0
means the battery is completely discharged. If the receiving device does not contain a battery or it cannot
provide charge status information, the CSP value should be set to 0xFF.
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4.13
4.13.1 4.13.2 4.13.3 4.13.4
4.13.5
UM3161
I2C interface
I2C interface
The STWBC86 can operate fully independent, that is, without being interfaced with a host system. In applications in which the STWBC86 is a part of peripherals managed by the host system, the two SDA and SCL pins could be connected to the existing I2C bus. The device works as an I2C slave and supports standard (100 kbps), fast (400 kbps), and fast mode plus (1 Mbps) data transfer modes. The STWBC86 has been assigned a 0x61 7-bit hardware address.
The pins are up to 3.3 V tolerant, and the pull-up resistors should be selected as a trade-off between communication speed (lower resistors lead to faster edges) and data integrity (the input logic levels must be guaranteed to preserve communication reliability). When the bus is idle, both SDA and SCL lines are pulled HIGH.
Data validity
The data on the SDA line remains stable during the high state of every SCL clock pulse. The high and low states of the SDA line only change when the SCL clock signal is low.
Start and stop conditions
Both the SDA and the SCL lines remain high when the I2C bus is not busy. A START condition is indicated by a high-to-low transition of the SDA line when SCL is HIGH, while the STOP condition is indicated by a low-to-high transition of the SDA line when SCL is HIGH. A STOP condition must be sent before each START condition.
Byte format
Every byte transferred over the SDA line contains 8 bits. Each byte received by STWBC86 is generally followed by an acknowledge (ACK) bit. The most significant bit (MSB) is transferred first. A single data bit is transferred during each clock pulse.
The device generates an ACK pulse (by pulling the SDA line low during the acknowledge clock pulse) to confirm a correct device address or data bytes reception.
Interface protocol
The interface protocol is composed of:
·
A start condition (START)
·
A device address + R/W bit (read =1 / write =0)
·
A register H address byte
·
A register L address byte
·
A sequence of n data bytes (each data byte must be acknowledged by the receiver)
·
A stop condition (STOP)
The register address byte determines the first register in which the read or write operation takes place. When a read or write operation is finished, the register address is automatically incremented.
Frequently used acronyms:
SAD: Slave Address; SUB AD: Subaddress; SR: Repeated start; R: Read; W: Write; SAK: Slave Acknowledge; MAK: Master Acknowledge; NMAK: No Master Acknowledge.
Writing to a single register
Writing to a single register begins with a START condition followed by the device address 0xC2 (7-bit device address plus R/W bit cleared), two bytes of the register pointer and the data byte to be written in the destination register. Each transmitted byte is acknowledged by the STWBC86 through an ACK pulse.
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Figure 51. Writing to a single register
UM3161
I2C interface
4.13.6
Writing to multiple registers with incremental addressing The STWBC86 supports writing to multiple registers with auto-incremental addressing. When data is written into a register, the register pointer is automatically incremented, therefore transferring data to a set of subsequent registers (also known as page write) is a straightforward operation.
Figure 52. Writing to multiple registers
4.13.7
Reading from a single register Reading from a single register begins with a START condition followed by the device address byte 0xC2 (7-bit device address plus R/W bit cleared) and two bytes of register pointer. A restart condition is then generated and the device address 0xC3 (7-bit device address plus R/W bit asserted) is sent, followed by data reading. The ACK pulse is generated by the STWBC86 at the end of each byte, but not for data bytes retrieved from the register. A STOP condition is finally generated to terminate the operation.
Figure 53. Reading from a single register
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4.13.8
UM3161
GPIOx and INTB pins
Reading from multiple registers with incremental addressing Similarly, to multiple bytes (page) writing, reading from subsequent registers relies on an auto-increment of the register: The master can extend data reading to the following registers by generating an ACK pulse at the end of each byte. Data reading starts immediately, and the stream is terminated by an NMAK at the end of the last data byte, followed by a STOP condition.
Figure 54. Reading from multiple registers
4.14 4.15
GPIOx and INTB pins
GPIO0 through GPIO7 are programmable general-purpose I/O pins. These pins can be configured as inputs or outputs (push-pull or open-drain) and assigned various functions.
Table 3. GPIO functions
Code I/O
Function
0x01 I Pull-up
0x02 I Pull-down
0x03 O Open drain (Active high)
0x04 O Open drain (Active low)
0x05 O Interrupt (Open drain)
0x06 O Firmware ready
0x1A O Power transfer on high when in power transfer, low in standby and ping state
0x1E O
Tx error high in error state which causes Tx to stop pinging. Conditions which cause this error can be set in the GUI
The INTB (GPIO6) pin is an interrupt output line that can be assigned to any internal interrupt condition and used to inform the host system about a specific event.
Interrupt registers
There are 4 bits (enable, clear, latch, and status) assigned to each interrupt sorted into separate tabs. The Enable tab can be used to either enable the corresponding interrupt (write), or to check whether the interrupt is already enabled (read). The Latch tab can be used to determine which interrupts have been triggered (read only). After being triggered, the bit remains set to 1 until cleared by writing a 1 into the corresponding clear register (write only). The Status tab can be used to determine which interrupt is being triggered at the moment (read only). The status bit goes back to zero after the triggering condition is removed.
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Figure 55. Interrupt registers
UM3161
Frequency hopping (fhop)
4.16
Note:
Frequency hopping (fhop)
One of the most common causes of ASK demodulation failure is noise produced by the adapter supplying power to the transmitter. The noise interferes with the communication, which may cause the decoding to fail, as the principal components of the noise are often close to the 2 kHz ASK communication frequency.
The STWBC86 features a frequency hopping (fhop) function that tries to improve the communication conditions by shifting the operating frequency by a set step whenever CE timeout occurs, as the new operating point may be less affected by the interference.
The fhop feature can be enabled and configured in the Tx Configuration section of the Tx Registers tab:
·
TX CE TO MAX defines the number of CEP timeouts that the device must register before terminating the
power transfer. When set to 1, the device terminates the power transfer immediately after registering a
CEP timeout. This register must never be set to 0. This should be considered especially when the device is
programmed by a host MCU! If the hopping feature is enabled, the device performs a frequency hop
whenever CEP timeout occurs. The maximum number of hops should be set conservatively. A high value
enables the transmitter to keep transmitting power for quite some time even after the receiver is removed.
·
TX CE TO FHOP enables the hopping feature. However, the device always waits for the number of CE
timeouts set in the TX CE TO MAX register even when hopping disabled!
·
TX FHOP defines the hop size in Hz. A positive value specifies a hop to a higher frequency, while a
negative value means a hop to a lower frequency. However, the frequency cannot be shifted beyond the
set minimum and maximum frequency (frequency range). Therefore, when a CEP timeout occurs, the
firmware first checks if the frequency hopping would shift the operating frequency outside of the range. If it
determines that a shift beyond the boundary would occur, the firmware starts frequency hopping in the
opposite direction instead. No other checks are performed, however.
It is recommended to set the TX FHOP*TX CE TO MAX product to be at most half of the frequency range. This ensures that the target frequency always remains within the set boundaries.
Operating frequency does not move beyond the boundary even if the target exceeds it.
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Figure 56. FHOP settings
UM3161
Frequency hopping (fhop)
The figure below shows an example of frequency hopping with the parameters defined above. Figure 57. FHOP example
1. Receiver is placed on the transmitter; transmitter regulates based on the CEP value; the Rx is removed shortly after.
2. CE timeout occurred, as there was no communication from the receiver. The transmitter performed four frequency hops (-2048 Hz step).
3. CE timeout occurred for the fifth time; the Tx ended the power transfer.
The same would apply in case of ASK demodulation error. If the transmitter is not able to decode the set number of CE packets in the row, power transfer is terminated. However, if a CE packet is decoded successfully, the transmitter resumes normal operation.
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4.17
UM3161
PID tuning
PID tuning
Power regulation of the power transmitter is controlled by a PID algorithm, as defined by the Qi specification. The default scaling factors for the respective parts are set according to the topology used A11a in the case of STEVAL-WBC86TX. Application specific requirements may demand adjustments in the topology, such as coil design or the input voltage (also defined by the topology specification). However, modifications to the circuit may affect the PID regulation performance, and consequently, may (or may not) require adjusting the PID parameters. For example: for a 6 V input voltage, the PID regulation may be too aggressive to achieve a stable regulation loop. Decreasing the scaling factors may improve the performance by slowing down the loop but may adversely impact other aspects of the regulation. Therefore, thorough testing is necessary after any adjustments to the PID parameters! The PID parameters can be found and adjusted in the Tx PID Regulation part of the TX Registers tab.
Figure 58. PID parameters
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STEVAL-WBC86TX description and operation
5
STEVAL-WBC86TX description and operation
5.1
STWBC86 default configuration
Table 4. Basic parameters
Parameter Transmitter topology TX bridge mode Minimum duty cycle Maximum duty cycle Minimum operating frequency Maximum operating frequency Ping duty cycle Ping frequency Ping duration Ping interval Overcurrent protection (OCP) Overvoltage protection (OVP) Overtemperature protection (OVTP) NTC protection Maximum CEP timeout count (for fhop feature) Fhop step Protection debounce FOD debounce
·
Enabled interrupts
Bridge mode change
CEP timeout
RPP timeout
Packet sent successfully
EPT from RX received
Foreign object detected
OCP triggered
OVP triggered
OVTP triggered
·
Enabled features
Foreign object detection
Auto ping
Fhop
Duty cycle regulation
·
EPT conditions after which the device does not start pinging automatically
Foreign object detected
OVP triggered
System error
Settings A11a Full sync 10 % 50 % 120 kHz 148 kHz 50 % 146 kHz 80 ms 2,000 ms 2 A 20 V 100 °C Disabled 3 1,920 kHz 0 4
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5.2
5.2.1
UM3161
Typical performance characteristics
·
GPIOs
No functions assigned
Typical performance characteristics
The following table shows charging performance of an STWBC86/STWLC38 (TX/RX) setup at various load currents, with the temperature being measured after 5 minutes of continuous operation.
Iout [mA] (RX) 200 500 700 1000
Iin [mA] (TX) 248 597 854 1294
Table 5. Charging performance
Vout [V] (RX) 5,01 5,01 5,01 5,01
Vin [V] (TX) 5,015 4,965 4,951 4,885
Trect [°C] (RX) 30 33 35 41
Trect [°C] (TX) 31,7 31,5 31,5 38,7
Power-up waveforms
The following figure shows power-up waveforms of an STWBC86 (TX) and STWLC38 (RX) setup. The transmitter and receiver coils are aligned and a 10 load is connected to the receiver output.
Figure 59. Power up waveform
Yellow Blue Red Orange
Color
Table 6. Signal legend for power up waveform
Vrect (RX) Vout (RX) AC1 (TX) Vin (TX)
Signal
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5.2.2
UM3161
Typical performance characteristics
Efficiency and spatial freedom in the XY plane
Efficiency is one of the most important metrics of wireless charging performance evaluation. Spatial freedom, size of the area in which a power receiver can be placed on the power transmitter, which still allows sufficient power to be transmitted, is another important metric.
Efficiency and spatial freedom of the STEVAL-WBC86TX were measured with STEVAL-WLC38RX as the receiver. The efficiency was measured from the transmitter DC input to the receiver DC output. The measurement does not include any power losses in the wall adapter or the USB Type-C® cable.
The test setup comprised of:
·
20 W PISEN wall adapter, model A829-120167C-EU1
·
USB Type-C® power cable from Vention, model COT
·
STEVAL-WBC86TX as transmitter
·
STEVAL-WLC38RX as receiver
·
Electronic load in CC mode, model BK Precision 8500.
The maximum efficiency achieved with this setup was 81%.
Efficiency curves for various misalignments in the X and Y axis are shown in the figures below:
Figure 60. X, Y axis for misalignment
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5.2.3
UM3161
Typical performance characteristics
Figure 61. Efficiency curve in X axis
85% 80% 75% 70% 65% 60% 55% 50% 45% 40% 35%
0.1
STEVAL-WBC86TX + STEVAL-WLC38RX (X-axis)
0.2 Center
0.3
0.4
0.5
0.6
0.7
Iout [A]
5 mm misalignment
10 mm misalignment
0.8
0.9
1
12 mm misalignment
Efficiency [%]
Efficiency [%]
Figure 62. Efficiency curve in Y axis
85% 80% 75% 70% 65% 60% 55% 50% 45% 40% 35%
0.1
STEVAL-WBC86TX + STEVAL-WLC38RX (Y-axis)
0.2 Center
0.3
0.4
0.5
0.6
0.7
Iout [A]
5 mm misalignment
10 mm misalignment
0.8
0.9
1
12 mm misalignment
Efficiency and spatial freedom in the Z-axis Z-axis distance between the coils, also known as charging gap, is an additional parameter that significantly affects charging performance. Therefore, the STEVAL-WBC86TX was also tested at various charging gap distances.
Efficiency curves for various misalignments in the Z-axis are shown in the figure below:
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UM3161
Typical performance characteristics
Figure 63. Efficiency curve in Z axis
STEVAL-WBC86TX + STEVAL-WLC38RX (Z-axis)
85%
75%
65%
55%
45%
35%
25%
15%
0.1
0.2
0.3
0.4
Io0u.5t [A]
0.6
0.7
0.8
0.9
1
3 mm gap
8 mm gap
10 mm gap
13 mm gap
Efficiency [%]
5.2.4
Z-distance of 3 mm is a typical value for most applications (2 mm on the TX side + 1 mm on the RX side). Clearly, the transmitter can deliver sufficient power even with 13 mm charging gap. However, efficiency is decreasing rapidly with increasing charging gap. Therefore, minimizing Z-distance whenever possible is recommended.
Thermal performance Thermal performance of the board with a 5 W load (5 V/1 A on the RX side) after 5 minutes of continuous operation.
Figure 64. Thermal performance
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6
6.1
6.1.1
6.1.2
6.1.3 6.1.4
UM3161
Designing a 5 W wireless power transmitter based on the STEVAL-WBC86TX evaluation board
Designing a 5 W wireless power transmitter based on the STEVALWBC86TX evaluation board
The design should begin with external component selection, as those components have a significant impact on the board performance. Modifications of the external components are also harder to implement after the board is manufactured and assembled.
External component design
The STWBC86 requires only a few external components to work properly. The design should begin with coil and series resonant capacitor selection, as those are the crucial parts of the design and affect most of the device's functions.
Coil selection
Coil selection is a complex problem, as there are several factors that influence the resulting performance. When selecting the coil, the designer should consider the coil's inductance, DCR, ACR, current rating, dimensions, maximum z-distance, and layout.
DCR, ACR (DC and AC resistance) should be kept as low as possible to minimize power loss caused by the current flowing through the coil.
Dimensions, maximum z-distance, and coil layout have to be considered to achieve the best coupling possible, as better coupling results in higher efficiency. Similar sized coils might offer a higher coupling factor, on the other hand a different sized RX/TX coil might offer greater freedom of positioning.
Using the default coil combination found in STMicroelectronics's EVKs should be a good starting point. For more information regarding coil selection, please refer to AN5961 or the Wireless Power Consortium's documentation, which describes coils used in the Qi certified topologies.
Series resonant capacitor selection
Selection of the series capacitors is greatly influenced by the transmitting coil design. The value should be selected so that the resulting circuit has its resonant peak located at, or very close to, 100 kHz. The following formula can be used to calculate the series capacitance value:
f=
1 2 L C
C=
L
1 2f 2
Voltage rating of the capacitors should consider that during operation, voltage generated across the capacitors is usually much higher than the input/output voltage of the system. Therefore, the minimum recommended voltage rating of the series resonant capacitors is 50 V.
Using C0G dielectric capacitors for the resonant circuit design is recommended to minimize temperature and biasing voltage influence on the capacitance value as much as possible.
For more information regarding capacitor value selection, please refer to Wireless Power Consortium's documentation, which describes capacitors used in the Qi certified topologies.
Vin and Vinv capacitors selection
Selection of the VIN and VINV capacitor's value is mostly a trade-off between load transition response time and capacitor cost and/or size. Capacitance of 30 uF for each of the nodes should be a good starting point. The voltage rating should respect the maximum input voltage. Ceramic X5R or X7R (preferred) dielectric capacitors are recommended.
Capacitor derating caused by temperature and DC bias should also be considered, as the capacitance decrease caused by those effects may be quite significant. Please refer to the capacitor datasheet for more information.
Hardware input protections
Hardware input overvoltage and overcurrent protections are recommended to avoid potential damage to the device caused by unusual conditions or wrong operation of the board.
A TVS diode is a good choice for overvoltage protection. Its breakdown voltage should be higher than the input voltage but should keep the input voltage safely below 27 V (absolute maximum rating of the input pins).
A fuse can be used as a cheap and simple overcurrent protection. The maximum input current should be limited to 2 A.
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Ring node voltage sensing
6.2
Ring node voltage sensing
Ring node (the node between transmitting coil and series resonant capacitor) voltage measurement is used as an additional indicator in foreign object detection. However, the DFT pin, used for the ring node voltage sensing, is only 1.98 V tolerant. In addition, the internal ADC supports only up to a 1.5 V reading. A resistor divider is therefore recommended to keep the DFT voltage below 1.5 V.
Figure 65. Ring node voltage sensing
To accurately measure the ring node voltage, the firmware requires the user to provide an accurate division factor in the GUI. The corresponding setting can be found in the Tx FOD Configuration section of the TX Registers tab. The division factor is defined as the ring node voltage divided by the DFT pin voltage.
Figure 66. Ring node divider configuration
6.3
PCB layout guidelines
·
Power tracks (AC1, AC2, VINV, VIN) and power ground tracks should be kept wide enough to sustain high
current. Duplicating these tracks in inner layers and adding vias is advisable wherever possible to lower
impedance as much as possible.
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6.4
6.4.1
6.4.2
UM3161
Reference code with STM32 development boards
·
AC1, AC2, BOOT1, and BOOT2 generate noise. Using shielding near these traces (by placing ground
planes below) is recommended.
·
Power ground carries the sum of ripple current and DC current from the inverter. Current return paths from
LDO capacitors should be routed separately from these high current paths.
·
AC1 and AC2 tracks should be routed close together to minimize the area of the resulting loop.
·
Communication (I2C) and sensing signals should be routed far from noise generating nets (AC1, AC2,
BOOT1, and BOOT2) to minimize the effects of interference induced from those high di/dt nets.
·
BOOT1, BOOT2 capacitors should be placed as close to the device as possible.
·
Input and inverter decoupling capacitors should be placed close to the device to minimize the area of high
current loops.
·
Auxiliary LDO capacitors should be placed as close to the device as possible.
·
Thermal performance and grounding can be enhanced by dedicating one layer as a ground plane. No
signal/power tracks should be routed on this layer to ensure ground integrity.
Reference code with STM32 development boards
Hardware requirements 1. STM32 development board (for example, STM32 Nucleo-144) 2. STEVAL-WBC86TX
Hardware connections 1. Connect the STWBC86's I2C pins to the master I2C bus. These signals require pull-up resistors to work
properly. 2. Power up STWBC86.
Figure 67. Pin connection between host and STWBC86 chip/evaluation board
STM32 Nucleo-144 board is used as an example.
Table 7. Pin connection between host (STM32) and STWBC86
STM32 Nucleo-144 5V (CN11.18) GND (CN11.20) I2C1_SDA (PB9 -> CN12.5) I2C1_SCL (PB8 -> CN12.3)
VIN GND SDA SCL
STEVAL-WBC86TX board
UM3161 - Rev 1
page 52/78
6.4.3 6.4.4
6.4.5
UM3161
Reference code with STM32 development boards
Software requirements 1. Patch/Configuration data in header (.h) file format STSW-WBC86FWBPP 2. STWLC NVM programming reference code 3. STM32CubeIDE
Source files The source files included in the reference code are listed below. 1. STWBC86.h
Provides NVM programming API and holds the structure and register definitions of STWBC86. 2. STWBC86.c
Main file which describes the NVM related programming sequences and I2C Write/WriteRead operations.
3. nvm_data.h Patch and Configuration data in Header file format to be programmed into the chip.
Reference code porting procedure 1. Create a new project in the STM32CubeIDE with an STM32 development board. Visit the
STMicroelectronics website for STM32CubeIDE documentation. 2. Enable the I2C and UART features of STM32.
Figure 68. Connectivity
3. Copy STWBC86.h, STWBC86.c, and nvm_data.h into the main directory (Core/Src). 4. Add the following code into Core/Src/main.c.
a. Include the Header file /* USER CODE BEGIN includes */ #include "STWBC86.h" /* USER CODE END includes */
b. Configure I2C and UART master in main() /* USER CODE BEGIN 2 */ // WLC - initialize I2C and UART peripheral hi2c = &hi2c1; huart = &huart3;
c. Execute NVM programming // WLC - display chip information char buff[PAGE_SIZE] = {0}; chip_info_show(buff); pr_info(buff); // WLC - perform NVM programming /* USER CODE END 2 */ pr_info(buff); nvm_program_show(buff); memset(buff, 0, PAGE_SIZE);
UM3161 - Rev 1
page 53/78
6.4.6 6.4.7
UM3161
Reference code with STM32 development boards
5. Add the following I²C error handling code below stm32f7xx_it.c when using STM32 FW_F7 V1.7.0 or lower. This handles the I²C NACK after performing a system reset. /** * @brief this function handles I2C1 error interrupt. */ voidI2C1_ER_IRQHandler(void) { /* USER CODE BEGIN I2C1_ER_IRQn 0 */ i2c_temp.Mode = hi2c1.Mode; i2c_temp.State = hi2c1.State; /* USER CODE END I2C1_ER_IRQn 0 */ HAL_I2C_ER_IRQHandler(&hi2c1); /* USER CODE BEGIN I2C1_ER_IRQn 1 */ hi2c1.Mode = i2c_temp.Mode; hi2c1.State = i2c_temp.State; /* USER CODE END I2C1_ER_IRQn 1 */ }
API 1. chip_info_show
Name Description Parameters Return value
int chip_info_show(char *buf)
Read chip information and return chip ID and version
char * buf Host allocated buffer to return chip information or error codes.
int
Length of the output buffer
2. nvm_program_show
Name Description Parameters Return value
int nvm_program_show(char *buf)
Program NVM with provided Header file.
char *
buf Host allocated buffer to return error codes.
int
Length of the output buffer
Error codes
Error code OK E_BUS_R E_BUS_W E_BUS_WR E_UNEXPECTED_OP_MODE E_NVM_WRITE E_INVALID_INPUT E_MEMORY_ALLOC E_UNEXPECTED_HW_REV E_TIMEOUT E_NVM_DATA_MISMATCH E_UNEXPECTED_CHIP_ID
Table 8. Error codes with descriptions
Value
Description
0x00000000 Success operation.
0x80000001 Error during I2C read operation.
0x80000002 Error during I2C write operation.
0x80000003 Error during I2C write read operation.
0x80000004 Invalid operating mode. NVM programming must be done in DC mode.
0x80000005 Failed to program NVM.
0x80000006 Invalid input parameters.
0x80000007 Failed to allocate memory buffer.
0x80000008 Invalid chip revision. Should match the provided nvm_data.h.
0x80000009 Timeout error when performing firmware operation.
0x8000000A Data mismatch with programmed data.
0x8000000B Invalid chip ID. Should match the provided nvm_data.h.
UM3161 - Rev 1
page 54/78
UM3161 - Rev 1
7
Schematic diagrams
Figure 69. STEVAL-WBC86TX circuit schematic (1 of 4)
AC2
AC1
Coil
760308111
P7
P8
11
11
COIL
COIL
AC1_COIL COIL 1
COIL 2
11 TP3
CBT1 BOOT2
47nF
CS1 100nF
CS2
CS3
CS4
100nF 100nF 100nF
11 TP4
CBT2 BOOT1
47nF
1
2
AC1_COIL
2
1
2
1
TX filter
D1
R1 5k1
C1 10n R3 220k C3 10n
AGND
1
2
1
2
1
2
1
2
2
1
11 1 2
P6 TP1
RING_NODE
D8 SMAJ22A R2 10k
1
C2
AGND
22n
VS
11
2
C4
D2
680p
N.M.
1
TP8
2
AGND AGND
R10 1k
C16
N.M.
R13 1k C17
N.M.
R20 560k
DFT
C19 10uF
R21 47k
AGND AGND
11 V1V8 V5V0
VINV
Decoupling caps
CR1 CR2 CR3 CR4 10uF 10uF 10uF 100nF
PGND
CO1 CO2 CO3 CO4 10uF 10uF 10uF 100nF
PGND TP6
VIN
C5
C6
1uF
100nF
DGND
C7
C8
4u7
100nF
DGND
UM3161
Schematic diagrams
page 55/78
UM3161 - Rev 1
Vin
Figure 70. STEVAL-WBC86TX circuit schematic (2 of 4)
J2 Shield
GND VBUS
CC2 CC1 VBUS GND
Shell
6 5 4 3 2 1
USB_C_6pin
1 2 3
J1 VIN
Header 2
GND
12 34 56
R17 5k1
1
2
1
2
R18 5k1
AGND
P1 Header 3X2
C15
R19
100pF 1M
2
GND
F1 3A
L1
1
Fuse
2
D7 SMAJ22A
1
GND
110R
2
VIN
11
VIN sense
TP2
1
Pull up resistors
RESET
LED
VOUT3V3 1 2
V1V8 V1V8
1
2
1
R6 R7 R8 4k7 4k7 4k7
2
1
R4 10k
RSTB
2
2
1
R5 100R
D3 RED
1
2
GPIO0
FT_SCL FT_SDA FT_INTB
UM3161
Schematic diagrams
page 56/78
UM3161 - Rev 1
Figure 71. STEVAL-WBC86TX circuit schematic (3 of 4)
C2 C1 BOOT2 B8 VSSP B7 AC1 B6 AC1 B5 VINV B4 VINV B3 AC2 B2 AC2 B1 VSSP A8 VSSP A7 AC1 A6 AC1 A5 VINV A4 VINV A3 AC2 A2 AC2 A1 VSSP
VINV VSSA VSSA
VIN VSSA VSSA VSSA
VIN VIN VIN VSSD
C3 C4
C5 C6 C7 C8 D1 D2 D3 D4 D5 D6 D7 D8 E1 E2 E3 E4
VINV VSSA
VSSA NC NC NC NC VIN VSSA VSSA VSSA NC NC NC VIN VIN VIN VSSD
NC BOOT2
VSSP AC1 AC1
VINV VINV
AC2 AC2 VSSP VSSP AC1 AC1 VINV VINV AC2 AC2 VSSP
U2 STWBC86_Bump72
SDA INTB
RSTB GPIO7 GPOI2 GPIO3 GPIO4 GPIO5
SCL VSSD VSSD VSSD VSSD VSSD GPIO0 GPIO1 V1V8 VSSA
J8 J7
J6 J5 J4 J3 J2 J1 H8 H7 H6 H5 H4 H3 H2 H1 G8 G7
SDA INTB
RSTB GPIO7 GPIO2 GPIO3 GPIO4 GPIO5 SCL VSSD VSSD VSSD VSSD VSSD GPIO0 GPIO1 V1V8 VSSA
VSSA V5V0 BOOT1 NC VS VIN VSSD VSSD VSSA VSSA V5V0 NTC DFT VSSD VSSD VSSD V1V8 VSSA
E5 E6 E7 E8 F1 F2 F3 F4 F5 F6 F7 F8 G1 G2 G3 G4 G5 G6
VSSA V5V0 BOOT1 VS VIN VSSD VSSD VSSA VSSA V5V0 NTC DFT VSSD VSSD VSSD V1V8 VSSA
UM3161
Schematic diagrams
STWBC86
VSSA VSSD VSSP
TP7 GND
AGNDDGNDPGND
V1V18
R12 2
1K
NTC
1 2
Header 2
AGND
page 57/78
UM3161 - Rev 1
Figure 72. STEVAL-WBC86TX circuit schematic (4 of 4)
USB-I2C convertor
VBUS DIO11 DIO12
2
1
D6 RED
R14 4k7
GND
2
1
D4 YELLOW
D5 GREEN
1
R15
R16
4k7
4k7
2
VOUT3V3 I2C communication
VBUS VOUT3V3 VCCIO
2 DCNF0
VCCIO
1
VCCIO
1
VCCIO VCCIO
1
R25 NA
GND
2 DCNF1
R26 R27
NA
10k
2 STEST_RESETN
2 DEBUGGER
2
1
2
R28 R29 10k 4k7
RESETN
C12 S1 100n
SW-SPST
1
1
Connectors
GND 1 2
Header 2
P3 11 GND1
1 2 Header 2 GND
FT_DP
R9
1
2
FT_DN33R
R31
1
2
33R
1
GND
1
C9 47pF
C10 47pF
U4
1 2 3
I/O1 GND I/O2
I/O1 VBUS
I/O2
6 5 4
USBLC6-2SC6
DP VBUS DN
2
2
FT_DN FT_DP
20 21
DM DP
STEST_RESETN 2
RESETN
3
DCNF0 4 DCNF1 5
VBUS
R30
1
2 26
5k1
25
DEBUGGER1
STEST_RESETIN RESETIN
DCNF0 DCNF1
VBUS_DET
FSOURCE
DEBUGGER
VCCIN 23 VOUT3V3 22
VCCIO 6
U3 FT260Q
DIO5/SCL DIO6/SDA DIO8/INT
12 13 15
DIO1/RTS DIO2/CTS DIO3/RXD DIO4/TXD
8 9 10 11
DIO0 DIO7 DIO9 DIO10 DIO11 DIO12 DIO13
7 14 16 17 18 27 28
FT_SCL FT_SDA FT_INTB
RTS CTS RXD TXD
DIO0 DIO7 DIO9 DIO10 DIO11 DIO12 DIO13
1 VCCIO
AGND
AGND
GND
FT_INTB FT_SCL FT_SDA
GND
P2
21 43 65 87
INTB SCL SDA
Header 4X2 GND
1 VOUT3V3
1 VBUS
1
1
C20
1
C21
C22
C23
C24
C25
4u7
100n 4u7
100n
4u7
100n
P14
16 15 14 13 12 11 10 9 8 7 6 5 4 3 2
1
Header 16
GND RSTB V5V0
INTB SDA SCL GPIO7 GPIO5 GPIO4 GPIO3 GPIO2 GPIO1 GPIO0
1 2 1 2 11
P10
DFT solder bridge, keep open
VINV TP5
VINV VINV sense
PGND
SHELL SHELL
CC1
CC2
1
1
R23 R24 5k1 5k1
2
2
GND GND
J3 USB-C connector 16pin
SHELL SHELL
GND A1 GNDB12 VBUSA4 VBUSB9 CC1 A5
B8 DP A6 DN B7 DN A7 DP B6
A8 CC2 B5 VBUSA9 VBUSB4 GNDA12 GND B1
GND GND VBUS VBUS CC1 SBU2 DP1 DN2 DN1 DP2 SBU1 CC2 VBUS VBUS GND GND
SHELL SHELL
1
C13
R11
100pF 1M
SHELL SHELL
2
GND GND
24 AGND 19 GND 29 GND
2
2
2
2
2
2
GND
GND
GND
GND
UM3161
Schematic diagrams
page 58/78
UM3161
Bill of materials
8
Item 1 2 3
4
5 6 7 8 9 10 11 12 13 14 15 16 17 18
19 20 21 22 23
Bill of materials
Table 9. STEVAL-WBC86TX bill of materials
Q.ty
Ref.
Value
Description
Manufacturer
Part number
4
C6, C8, CO4, CR4
100nF, C_0402, 50V, 10%,
Min 50V; X5R/X7R
Wurth
885012205092
2
C16, C17 N.M.
N.M.
N.M.
6
CO1, CO2, CO3, CR1, CR2, CR3
10uF, C_0805, 35V, 10%,
Min 35V; X5R/X7R
Murata
GRM21BR6YA106KE43 L
TP1, TP2,
6
TP3, TP4, N.M., J_TESTPOINT_1.1mm, PIN
TP6, TP8
N.M.
N.M.
R17, R18,
5
R23, R24, 5k1, R_0402, 62.5m W, 5%, Resistor
R30
Yageo
RC0402JR-075K1L
4
C12, C21, C23, C25
100n, C_0402, 50V, 10%,
Min 6.3V; X5R/X7R
Wurth
885012205092
4
CS1, CS2, CS3, CS4
100nF, C_1206, 50V, 5%,
Min 50V; C0G
Murata
GRM31C5C1H104JA01 L
GND,
4
GND1, VIN, HDR1X2,
VINV
Header 2
Harwin
M20-9730245
3
R4, R27, R28
10k, R_0402, 62.5m W, 5%, Resistor
Yageo
RC0402JR-1310KL
R6, R7, R8,
7
R14, R15, 4k7, R_0402, 62.5m W, 5%, Resistor
R16, R29
Yageo
RC0402JR-134K7L
2
C1, C3
10n, C_0402, 50V, 10%,
Min. 50V; X5R/X7R
Wurth
885012205067
2
C9, C10
47pF, C_0402, 50V, 5%,
Min. 6.3V; X5R/X7R
Wurth
885012005059
2
C13, C15
100pF, C_0402, 50V, 10%,
Min. 50V; X5R/X7R
Wurth
885012205055
1
C19
10uF, C_0603, 6.3V, 20%,
Min. 6.3V; X5R/X7R
Wurth
885012106006
4
C7, C20, C22, C24
4u7, C_0402, 6.3V, 20%,
Min. 6.3V; X5R/X7R
Wurth
885012105008
2
CBT1, CBT2 47nF, C_0402, 50V, 10%,
Min. 50V; X5R/X7R
Murata
GRT155R71H473KE01 D
2
D3, D6
D_0603_LED, 2V, 20mA,
RED
Wurth
150060RS75000
2
D7, D8
D_SMA (DO-214AC), 22V, 400W,
Diode
Littelfuse
SMAJ22A
P7, P8
2
connect coil 760308111
2mm_PIN,
(item 27)
COIL
N.M.
N.M.
2
R9, R31
33R, R_0402, 62.5m W, 5%, Resistor
Yageo
RC0402FR-0733RL
2
R10, R13 1k, R_0402, 62.5m W, 5%, Resistor
Yageo
RC0402JR-071KA
2
R11, R19 1M, R_0402, 62.5m W, 5%, Resistor
Yageo
RC0402JR-7D1ML
1
R12
1k, R_0603
Resistor
Yageo
RC0603JR-071KL
UM3161 - Rev 1
page 59/78
Item 24
25
26
27
28 29 30 31 32
33
34 35 36 37 38 39 40
41
42 43 44 45 46 47 48 49 50 51 52 53 54 55
UM3161
Bill of materials
Q.ty
Ref.
Value
Description
Manufacturer
Part number
1
C2
22n, C_0402, 50V, 20%,
Min. 50V; X5R/X7R
Murata
GCM155R71H223MA55 D
1
C4
680p, C_0402, 50V, 10%,
Min. 50V; X5R/X7R
Wurth
885012205060
1
C5
1uF, C_0402, 10V, 20%,
Min. 16V; X5R/X7R
Wurth
885012105012
COIL
1
connect to P7, P8 (item
19)
Wurth
760308111
1
D1
DIOMELF1006N
Diode
Diodes Incorporated
1N4448HLP-7
1
D2
N.M., D_SOD882
Diode
N.M.
N.M.
1
D4
D_0603_LED, 2V, 20mA
YELLOW
Wurth
150060YS55040
1
D5
D_0603_LED, 2V, 20mA
GREEN
Wurth
150060VS55040
1
F1
F_SMD_1206_DIN3216M 65V, 3A
Fuse
Bourns
SF-1206S300W-2
1
J1
J_PTH_POWERJACK_2.1M M, 18V, 1.5A
Barrel connector
Kubiconn
163-179PH-EX
1
J2
USB_C_UJC-HP-3-SMT-TR, 3A
USB_C_6pin
CUI devices
UJC-HP-3-SMT-TR
1
L1
L_SMD_0805_DIN2012M, 3A Inductor
Wurth
742792025
1
NTC
N.M., HDR1X2
Header 2
N.M.
N.M.
1
P1
HDR2X3
Header 3X2
Harwin
M20-9720345
1
P2
HDR2X4
Header 4X2
Harwin
M20-9720445
1
P3
N.M., 2mm_PIN
PIN
N.M.
N.M.
1
J3
J_USB4105-GF-A-120, 20V, 5A
USB Type-C® connector 16-pin
Wurth
629722000214
1
P6 solder together
P_solderingoption_02
Solder bridge, keep close
N.M.
N.M.
1
P10 keep open
P_solderingoption_02
Solder bridge, keep open
N.M.
N.M.
1
P14
HDR1X16
Header 16
Harwin
M20-9991645
1
R1
5k1, R_0402, 62.5m W, 1% Resistor 1%
Yageo
RC0402FR-075K1L
1
R2
10k, R_0402, 62.5m W, 1% Resistor 1%
Yageo
RC0402FR-0710KL
1
R3
220k, R_0402, 62.5m W, 1% Resistor 1%
Yageo
RC0402FR-07220KL
1
R5
100R, R_0402, 62.5m W, 5% Resistor
Yageo
AR0402JR-07100RL
1
R20
560k, R_0402, 62.5m W, 1% Resistor 1%
Yageo
RC0402FR-07560KL
1
R21
47k, R_0402, 62.5m W, 1% Resistor 1%
Yageo
RC0402FR-0747KL
2
R25, R26 N.M., R_0402, 5%
Resistor
N.M.
N.M.
1
S1
SWITCH_P-DT2112C
SW-SPST
DIPTRONIC
P-DT2112C
1
TP5
N.M., J_TESTPOINT_1.1mm PIN
N.M.
N.M.
1
TP7
N.M., P_SMD_TEST_12
Test Point
N.M.
N.M.
1
U2
B_72B_240um
STWBC86_Bump 72
STMicroelectronic s
STWBC86
1
U3
U_WQFN28
FT260Q
FTDI
FT260Q-T
UM3161 - Rev 1
page 60/78
Item 56 57
58 59 60 61 62 63
Q.ty
Ref.
Value
1
U4
V_SOT23-6L
Jumpers
short SDA,
SCL, INT,
and POWER
4
coming from
USB Type-
C® (in the
center of 2x3
header)
Both sides
tape. Total
length 32m,
means 220
1
PCBs
(dimension
12.7x13mm)
, 1mm
thickness
Standoff
Material
6
requirement
UL94 - V0 or
V1
Untreated
standoff
4
Material requirement
UL94 - V0 or
V1
Screw with
flat head M3
4
Material requirement
UL94 - V0 or
V1
Screw M3
Material
2
requirement
UL94 - V0 or
V1
Custom
spacer
STEVAL-
WBC86TX
1
rev A
Material
requirement
UL94 - V0 or
V1
UM3161
Bill of materials
Description
USBLC6-2SC6, SOT23-6L
Manufacturer
Part number
STMicroelectronic s
USBLC6-2SC6
Short SDA, SCL, INT, and POWER coming from USB Type-C® (in the center of 2x3 header)
Wurth
60900213421
3M
5958FR(1/2"X36YD)
Standoff, hex metric, M3
Wurth
Standoff, M3, untreated
Wurth
970080365 960060042
Screw M3 with flat head
Essentra
50M030050I016
Screw M3
Wurth
97790603111
Vendor for plexi Vendor for plexi
UM3161 - Rev 1
page 61/78
9
STEVAL-WBC86TX PCB layout
Figure 73. Top layer
UM3161
STEVAL-WBC86TX PCB layout
UM3161 - Rev 1
page 62/78
Figure 74. Inner1 layer
UM3161
STEVAL-WBC86TX PCB layout
UM3161 - Rev 1
page 63/78
Figure 75. Inner2 layer
UM3161
STEVAL-WBC86TX PCB layout
UM3161 - Rev 1
page 64/78
Figure 76. Bottom layer
UM3161
STEVAL-WBC86TX PCB layout
UM3161 - Rev 1
page 65/78
UM3161
Board versions
10
Board versions
Table 10. STEVAL-WBC86TX versions
Finished good
Schematic diagrams
STEVAL$WBC86TXA (1)
STEVAL$WBC86TXA schematic diagrams
1. This code identifies the STEVAL-WBC86TX evaluation board first version.
Bill of materials STEVAL$WBC86TXA bill of materials
UM3161 - Rev 1
page 66/78
UM3161
Regulatory compliance information
11
Regulatory compliance information
Formal Product Notice Required by FCC:
For evaluation only; not FCC approved for resale FCC NOTICE - This kit is designed to allow: (1) Product developers to evaluate electronic components, circuitry, or software associated with the kit to determine whether to incorporate such items in a finished product and (2) Software developers to write software applications for use with the end product. This kit is not a finished product and when assembled may not be resold or otherwise marketed unless all required FCC equipment authorizations are first obtained. Operation is subject to the condition that this product not cause harmful interference to licensed radio stations and that this product accept harmful interference. Unless the assembled kit is designed to operate under part 15, part 18 or part 95 of this chapter, the operator of the kit must operate under the authority of an FCC license holder or must secure an experimental authorization under part 5 of this chapter 3.1.2.
Formal Product Notice Required by Industry Canada
For evaluation purposes only. This kit generates, uses, and can radiate radio frequency energy and has not been tested for compliance with the limits of computing devices pursuant to Industry Canada (IC) rules. À des fins d'évaluation uniquement. Ce kit génère, utilise et peut émettre de l'énergie radiofréquence et n'a pas été testé pour sa conformité aux limites des appareils informatiques conformément aux règles d'Industrie Canada (IC).
Notice for the European Union
The kit STEVAL-WBC86TX is in conformity with the essential requirements of the Directive 2014/53/EU (RED) and of the Directive 2015/863/EU (RoHS). Applied harmonized standards are listed in the EU Declaration of Conformity. Compliance to EMC standards in Class A (industrial intended use).
Notice for the United Kingdom
The kit STEVAL-WBC86TX is in compliance with the UK Radio Equipment Regulations 2017 (UK SI 2017 No. 1206 and amendments) and with the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment Regulations 2012 (UK SI 2012 No. 3032 and amendments). Applied standards are listed in the UK Declaration of Conformity. Compliance to EMC standards in Class A (industrial intended use).
UM3161 - Rev 1
page 67/78
UM3161
Thermal measurements
Appendix A Thermal measurements
Thermal measurements on the Board tested at 25C ambient temperature.
Figure 77. Temperature Before Power Transfer Maximum 25C on STEVAL-WBC86TX
UM3161 - Rev 1
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Figure 78. Maximum Temperature of the Board after 2hours (40.8C) - 5W power transfer STEVALWLC38RX
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Figure 79. Maximum Temperature of the Board and Plastic case after 2hours (33.5C) - 5W power transfer
Note:
The ambient temperature should not exceed 65C
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Revision history
Date 20-Jul-2023
Table 11. Document revision history
Revision 1
Initial release.
Changes
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1 Reference design specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Overview of the board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2.1 Test points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 Basic operating modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3 Graphical user interface (GUI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.1 Connecting STWBC86 to PC GUI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2 Patch and Configuration files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.3 Configuration file generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.4 Header file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.5 Header file generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.6 Programming the device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4 Device description and operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 4.1 System block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.2 Integrated power inverter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.3 ADC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.4 LDOs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.5 Power-up sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.6 UVLO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.7 Chip reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.8 Protections overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.8.1 Overcurrent protection (OCP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.8.2 Overvoltage protection (OVP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4.8.3 Overtemperature protection (OVTP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4.8.4 NTC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4.9 Foreign object detection (FOD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 4.9.1 FOD tuning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 4.10 EPT reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 4.11 WPC Qi wireless power transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 4.11.1 Wireless power interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 4.12 Bidirectional communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 4.12.1 ASK communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 4.12.2 FSK communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 4.12.3 Most common Qi communication packets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 4.13 I2C interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 4.13.1 Data validity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
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4.13.2 Start and stop conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 4.13.3 Byte format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 4.13.4 Interface protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 4.13.5 Writing to a single register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 4.13.6 Writing to multiple registers with incremental addressing . . . . . . . . . . . . . . . . . . . . . . . . . 40 4.13.7 Reading from a single register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 4.13.8 Reading from multiple registers with incremental addressing . . . . . . . . . . . . . . . . . . . . . . 41 4.14 GPIOx and INTB pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 4.15 Interrupt registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 4.16 Frequency hopping (fhop) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 4.17 PID tuning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
5 STEVAL-WBC86TX description and operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45 5.1 STWBC86 default configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 5.2 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.2.1 Power-up waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 5.2.2 Efficiency and spatial freedom in the XY plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 5.2.3 Efficiency and spatial freedom in the Z-axis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 5.2.4 Thermal performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
6 Designing a 5 W wireless power transmitter based on the STEVAL-WBC86TX evaluation board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50 6.1 External component design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
6.1.1 Coil selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 6.1.2 Series resonant capacitor selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 6.1.3 Vin and Vinv capacitors selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 6.1.4 Hardware input protections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 6.2 Ring node voltage sensing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 6.3 PCB layout guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 6.4 Reference code with STM32 development boards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 6.4.1 Hardware requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 6.4.2 Hardware connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 6.4.3 Software requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 6.4.4 Source files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 6.4.5 Reference code porting procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 6.4.6 API . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 6.4.7 Error codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
7 Schematic diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55 8 Bill of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
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9 STEVAL-WBC86TX PCB layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62 10 Board versions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66 11 Regulatory compliance information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67 Appendix A Thermal measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71 List of tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75 List of figures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76
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List of tables
List of tables
Table 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Table 9. Table 10. Table 11.
STEVAL-WBC86TX target specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Connectors and test points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 GPIO functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Basic parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Charging performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Signal legend for power up waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Pin connection between host (STM32) and STWBC86 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Error codes with descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 STEVAL-WBC86TX bill of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 STEVAL-WBC86TX versions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
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List of figures
Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Figure 15. Figure 16. Figure 17. Figure 18. Figure 19. Figure 20. Figure 21. Figure 22. Figure 23. Figure 24. Figure 25. Figure 26. Figure 27. Figure 28. Figure 29. Figure 30. Figure 31. Figure 32. Figure 33. Figure 34. Figure 35. Figure 36. Figure 37. Figure 38. Figure 39. Figure 40. Figure 41. Figure 42. Figure 43. Figure 44. Figure 45. Figure 46. Figure 47. Figure 48. Figure 49. Figure 50. Figure 51. Figure 52. Figure 53.
STEVAL-WBC86TX board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 STEVAL-WBC86TX evaluation board features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Connectors and test points. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 GUI connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 GUI device connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Generation of configuration file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Version of the configuration file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Saving of the configuration file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Header generator - chip selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Header generation - pop up window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Header generation - save header file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Programming the device by header file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Generating the header file by patch and configuration files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 System block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 H-bridge mode settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 GUI charts monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 OCP settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 OVP settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 OVTP settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 NTC connection on board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 NTC settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Disable FO detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Add a new dataset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Display dataset in plot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Enable auto scroll . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Additional dataset options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Line properties - dashed/solid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Line properties - color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Logged data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Delete a single data point. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Spot wrong data point in plot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Plot logged data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Ploss threshold. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 CTC threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Unsutiable parameter values highlighted in red . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Load tuned parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Enable FOD and set FOD debounce . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 EPT reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Received message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 EPT interrupt setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Protection debounce setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 EPT reping settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Power transfer start up sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Amplitude modulation of the Power Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Example of a differential bi-phase encoding scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Example of the asynchronous serial format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 ASK communication example - high load current. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 ASK communication - no load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Example of differential bi-phase encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Format of the three defined responses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Writing to a single register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Writing to multiple registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Reading from a single register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
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List of figures
Figure 54. Figure 55. Figure 56. Figure 57. Figure 58. Figure 59. Figure 60. Figure 61. Figure 62. Figure 63. Figure 64. Figure 65. Figure 66. Figure 67. Figure 68. Figure 69. Figure 70. Figure 71. Figure 72. Figure 73. Figure 74. Figure 75. Figure 76. Figure 77. Figure 78. Figure 79.
Reading from multiple registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Interrupt registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 FHOP settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 FHOP example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 PID parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Power up waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 X, Y axis for misalignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Efficiency curve in X axis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Efficiency curve in Y axis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Efficiency curve in Z axis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Thermal performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Ring node voltage sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Ring node divider configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Pin connection between host and STWBC86 chip/evaluation board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Connectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 STEVAL-WBC86TX circuit schematic (1 of 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 STEVAL-WBC86TX circuit schematic (2 of 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 STEVAL-WBC86TX circuit schematic (3 of 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 STEVAL-WBC86TX circuit schematic (4 of 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 Top layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 Inner1 layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Inner2 layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Bottom layer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Temperature Before Power Transfer Maximum 25C on STEVAL-WBC86TX . . . . . . . . . . . . . . . . . . . . . . . . 68 Maximum Temperature of the Board after 2hours (40.8C) - 5W power transfer STEVAL-WLC38RX . . . . . . . . 69 Maximum Temperature of the Board and Plastic case after 2hours (33.5C) - 5W power transfer. . . . . . . . . . . 70
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IMPORTANT NOTICE READ CAREFULLY STMicroelectronics NV and its subsidiaries ("ST") reserve the right to make changes, corrections, enhancements, modifications, and improvements to ST products and/or to this document at any time without notice. Purchasers should obtain the latest relevant information on ST products before placing orders. ST products are sold pursuant to ST's terms and conditions of sale in place at the time of order acknowledgment. Purchasers are solely responsible for the choice, selection, and use of ST products and ST assumes no liability for application assistance or the design of purchasers' products. No license, express or implied, to any intellectual property right is granted by ST herein. Resale of ST products with provisions different from the information set forth herein shall void any warranty granted by ST for such product. ST and the ST logo are trademarks of ST. For additional information about ST trademarks, refer to www.st.com/trademarks. All other product or service names are the property of their respective owners. Information in this document supersedes and replaces information previously supplied in any prior versions of this document.
© 2023 STMicroelectronics All rights reserved
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