RT7202K Highly Integrated USB PD Type-C Controller for SMPS

General Description

The RT7202K is a simple yet flexible controller for multipurpose USB PD applications, capable of operating as either a source or a sink. When configured as a source, it can be used in off-line AC-DC converters, integrating a shunt regulator, constant voltage (CV), and constant current (CC) control loops with a programmable reference voltage to meet Programmable Power Supply (PPS) specifications. When combined with an external buck or buck-boost controller, it can form a DC-DC converter, such as a car charger, also meeting PPS specifications. As a sink, it offers a simple, low-cost, and flexible solution for requesting power from a source. Specific variants like RT7202KD/KJ/KT include an I²C interface and two GPIOs for flexible control by a master MCU.

Ordering Information

The RT7202K is available in various configurations, identified by a programmed firmware code (AABBX), where AA denotes the Application Code, BB the Model Code, and X the Customer Approved Version Code. Package types include WQFN-16L 4x4 (W-Type) for RT7202KD/KJ/KT and SOP-10 for RT7202KE/KF/KH/KP. Lead plating is available as Green (Halogen Free and Pb Free). The RT7202K version can be referenced from the Version Table.

Richtek products are RoHS compliant and compatible with IPC/JEDEC J-STD-020, suitable for SnPb or Pb-free soldering processes.

Features

• Protocols Supported: USB PD 2.0 and 3.0 (PPS), Other Proprietary Protocols
• Highly Integrated:
  • Embedded MCU with Mask-ROM (24kB), OTP-ROM (8kB for RT7202KD/KE/KF or 16kB for RT7202KH/KJ/KP/KT), and SRAM (2kB).
  • Embedded BMC Transceiver.
  • Wide VDD Operation Range: 3V to 22V.
  • Built-in Shunt Regulator for Constant-Voltage and Constant-Current Regulation.
  • Built-in 10-bit Analog-to-Digital Converter (ADC).
  • Programmable Cable Compensation.
  • BLD Pin for Quick Discharge of Output Capacitor (RT7202KD/KJ).
  • VDD Pin for Quick Discharge of Output Capacitor (RT7202KE/KF/KH/KP/KT).
  • USBP Pin for Direct Drive of External Blocking N-MOSFET.
  • Power-Saving Mode in Standby Mode.
• Protection:
  • Adaptive Over-Voltage Protection.
  • Adaptive Under-Voltage Protection.
  • Firmware-Programmable Over-Current Protection.

Applications

• USB PD Type-C Chargers/Adapters for Smartphones, Notebooks, Tablets, and All Other Electronics.
• USB PD Extension Cores with Offline AC-DC Converters.

Marking Information

For specific marking information, please contact a Richtek sales representative or a Richtek distributor.

Pin Configuration

The RT7202K is available in WQFN-16L 4x4 and SOP-10 packages. Detailed pin assignments and functions are provided for each package type.

Diagram: Top view of WQFN-16L 4x4 package (RT7202KD/KJ) showing pin numbers and names (GND, USBP, NC, V2, DM/SDA, CC1, CC2, DP/SCK, CS+, CS-, VFB, IFB, VBUS/GPIO1, OPTO, VDD, BLD/GPIO2). Diagram: Top view of WQFN-16L 4x4 package (RT7202KT) showing pin numbers and names (VBUS, USBP, V2, DP, GND, RT, IFB, VFB, CS-, CS+, CC2, CC1, DM, NC, OPTO, VDD). Diagram: Top view of SOP-10 package (RT7202KE) showing pin numbers and names (VDD, GND, USBP, V2, CC1, CC2, CS-, VFB, IFB, OPTO). Diagram: Top view of SOP-10 package (RT7202KF/KP) showing pin numbers and names (VDD, GND, USBP, V2, DM, CC1, CC2, CS-, VFB, OPTO). Diagram: Top view of SOP-10 package (RT7202KH) showing pin numbers and names (GND, USBP, V2, CC1, CC2, CS+, CS-, VFB, OPTO, VDD).

RT7202K Version Table

A table details the specifications for different RT7202K versions (RT7202KD, KE, KF, KH, KJ, KP, KT), including Output Voltage Supported, VOUT Scaling Factor, DP/DM Pin availability, Blocking MOSFET Driver type, IFB Pin, VBUS Pin, BLD Pin, Built-in FB Resistors, and OTP ROM size.

Simplified Application Circuits

Schematic diagrams illustrate typical application circuits for the RT7202K in both sink and source configurations for various package types (RT7202KD/KJ, RT7202KE, RT7202KF/KP, RT7202KH, RT7202KT). These circuits show the integration of the RT7202K with external components like MOSFETs, resistors, capacitors, and optocouplers for power conversion and control.

Functional Pin Description

Detailed descriptions of each pin's function are provided for RT7202KD/KJ, RT7202KE, RT7202KF/KP, RT7202KH, and RT7202KT variants, specifying pin number, name, type (PWR, GND, D IO, A/D IO, AI, AO), and its specific function within the circuit.

Functional Block Diagrams

Block diagrams illustrate the internal architecture of the RT7202K for different variants (RT7202KD/KJ, RT7202KE, RT7202KF/KP, RT7202KH, RT7202KT). These diagrams show the interplay between the MCU, ROM, SRAM, ADC, DAC, regulators, and various interface blocks like CC, USBP, OPTO, and CS.

Operation

The RT7202K is a highly integrated secondary-side USB PD Type-C controller designed for off-line AC-DC converters. It features two regulated DC output voltages (V5 and V2) for internal circuitry and an MCU. A bypass capacitor at V2 improves LDO stability.

Constant-Voltage (CV) Regulators

A CV regulator connects to the OPTO pin. Its feedback loop is similar to a TL431 shunt regulator but offers a wider VOPTO range (0.3V to 25V). The OPTO pin remains high-impedance below VDD_ON threshold for smooth power-on. The reference voltage (VREF_CV) comes from an embedded DAC, with analog output range from 0.15V to 2.2V, enabling 10mV output voltage resolution for precise CV regulation.

Constant-Current (CC) Regulators (For RT7202KD/KE/KJ/KT)

A CC regulator also connects to the OPTO pin, with an analog current loop output range from 0 to 1.5V (typical) via a 10-bit DAC.

Current-Sense Amplifier

The RT7202K includes a current-sense amplifier with virtually zero input offset voltage and programmable gain (20 or 40). The amplified current signal is sent to the MCU via an ADC for conversion, enabling output current monitoring and over-current protection.

Interface of DP and DM (For RT7202KD/KF/KJ/KP/KT)

The DP and DM pins connect to the MCU via an ADC and can be reprogrammed for analog/digital input/output functions.

Interface of CC1 and CC2

The CC1 and CC2 pins ensure USB PD Type-C specification compliance. When configured as a Downstream Facing Port (DFP), they advertise current capabilities (80µA, 180µA, 330µA) to an Upstream Facing Port (UFP) as default USB current, 1.5A, and 3.0A.

Open-Drain Drivers for BLD and VBUS Pins

The BLD pin acts as a bleeder to discharge output capacitors upon device detachment or to a lower output voltage. The VBUS pin also serves as a bleeder and provides real-time VBUS voltage detection (except for RT7202KT).

Blocking MOSFET Control (USBP)

The RT7202K uses a push-pull driver for an external blocking N-MOSFET. This driver ensures smooth turn-on for capacitive loads and quick turn-off during faults. The N-MOSFET turns on upon Type-C communication setup or detection of a 5.1kΩ resistor on CC1/CC2. It turns off if VOUT over-voltage occurs or if VOUT is shorted to GND, protecting the UFP.

Output Over-Voltage Protection

The RT7202K provides fast turn-off of the blocking N-MOSFET for VOUT over-voltage protection. If the voltage related to VDD exceeds the programmable threshold VVOUT_OVP, the USBP pin is pulled low and latched until VDD drops below VVDD_OFF. The MCU has a debounce time of approximately 50µs for the latched OPTO signal.

Thermal Considerations

Junction temperature must not exceed the absolute maximum rating (TJ(MAX)) to prevent device damage. Maximum power dissipation (PD(MAX)) depends on thermal resistance (JA), PCB layout, airflow, and ambient temperature (TA), calculated as PD(MAX) = (TJ(MAX) - TA) / JA. For continuous operation, the maximum junction temperature is 125°C. Thermal resistance (JA) varies by package: WQFN-16L 4x4 is 256.4°C/W, and SOP-10 is 194.2°C/W, based on JEDEC 51-3 standards. Derating curves illustrate power dissipation reduction at higher ambient temperatures.

Electrical Characteristics

Detailed electrical characteristics are provided for VDD section, regulators, internal bias, current sense amplifier, DP/DM section, CC1/CC2 section, and USBP section, including parameters like turn-on/off thresholds, operating currents, protection thresholds, voltage gains, bandwidths, and timing characteristics across specified test conditions.

Typical Operating Characteristics

Graphs illustrate the typical behavior of key parameters (e.g., VDD_ON, VDD_OFF, IDD_START, IDD_OP, IDD_SLEEP, VVDD_OVP, IDD_DISCH, VBIAS_V2, VADC_MAX, VDAC_MAX_CV, KVOUT, RON_OPTO, RL_VBUS, etc.) as a function of temperature.

Outline Dimensions and Footprint Information

Mechanical dimensions for the W-Type 16L QFN 4x4 package and the 10-Lead SOP Plastic Package are provided in millimeters and inches. Footprint dimensions for the WQFN and SOP packages are also detailed, including pin pitch, land pattern dimensions, and tolerances.