ANALOG DEVICES LTC9111, IEEE 802.3cg SPoE PD Controller Owner’s Manual
FEATURES
► IEEE 802.3cg-compliant SPoE PD
► Supports serial communication classification protocol (SCCP)
ONLINE RESOURCES
► Schematic, PCB layout, and bill of materials
GENERAL DESCRIPTION
The EVAL-LTC9111-AZ is an evaluation motherboard featuring the LTC9111, an IEEE 802.3cg-compliant single pair power over Ethernet (SPoE) powered device (PD) controller.
With the LTC9111 wide operating range of 2.3V to 60V, the EVAL- LTC9111-AZ may be configured with class jumpers to IEEE 802.3cg 24V power classes (Class 10 to Class 12) or 52V power classes (Class 13 to Class 15).
The EVAL-LTC9111-AZ motherboard headers (J1, J2, and J3) connect to SPoE shields, the EVAL-10BT1L-MCS-AZ (Class 10 to Class 14) or the EVAL-10BT1L-MCS-BZ (Class 15). The EVAL- LTC9111-AZ motherboard with a shield connects via a single pair Ethernet (SPE) cable to an IEEE 802.3cg SPoE power sourcing equipment (PSE) for power.
The EVAL-LTC9111-AZ incorporates both IEEE 802.3cg-compliant wakeup signature and SCCP-based classification.
EVALUATION BOARD PHOTOGRAPH
PLEASE SEE THE LAST PAGE FOR AN IMPORTANT WARNING AND LEGAL TERMS AND CONDITIONS.
REVISION HISTORY
7/2025—Revision 0: Initial Version
EVALUATION BOARD QUICK START PROCEDURE
EVAL-LTC9111-AZ OPERATION
The EVAL-LTC9111-AZ is an IEEE 802.3cg SPoE PD motherboard. Refer to Figure 2 to Figure 5 and Table 1 for proper equipment setup.
Refer to Figure 2 for the EVAL-LTC9111-AZ evaluation with an EN enabled DC-DC converter and Figure 3 for evaluation with a resistive or active load.
Follow these steps on how to connect the PD:
- Set PD class with the CLASSV and CLASSC jumpers according to Table 1.
- Align the EVAL-10BT1L-MCS-AZ SPoE (Class 10 to Class 14) shield or the EVAL-10BT1L-MCS-BZ (Class 15) SPoE shield over the headers on the EVAL-LTC9111-AZ motherboard as shown in Figure 4. Push down firmly on the shield until all headers are flush. Verify no pins are sticking out.
Note that the last two female pins of P1 (the longer connector) must be left floating. - Set the P4 jumper to CONNECT when using the EVAL-10BT1L- MCS-AZ SPoE (Class 10 to Class 14) shield to connect the on-board sense snubber; set the P4 jumper to DISCONNECT when using the EVAL-10BT1L-MCS-BZ SPoE (Class 15) shield to disconnect the on-board sense snubber.
- Connect the output of the IEEE 802.3cg-compliant PSE to the SPoE shield. A compliant PSE classifies the EVAL-LTC9111-AZ SPoE PD which responds with the class set in Table 1. After connection is established, verify LED1 is lit. This LED indicates a successful classification followed by power-up.
Table 1. Class Jumper Selection, PD Class, PD On Range, and PD Power
¹N/A means not applicable.
EVALUATION BOARD QUICK START PROCEDURE
EVAL-LTC9111-AZ DEMONSTRATION CIRCUIT
SHIELD INSTALLATION
The EVAL-LTC9111-AZ PD motherboard can accept one media converter shield. For Class 10 to Class 14 evaluations, install the EVAL-10BT1L-SMC-AZ. For Class 15 evaluation, install the EVAL-10BT1L-SMC-BZ.
When inserting a shield on to the motherboard, align the two short male headers of the shield with the two short female headers at a port on the motherboard (see Figure 4). The longer header naturally aligns. The last two pins of the longer header on the motherboard are reserved for future use and do not have pins inserted in them. Insert the shield until the headers are flush with each other. Before proceeding, verify no pins are sticking out indicating a misalignment.
Note that powering the EVAL-LTC9111-AZ motherboard with a misaligned shield can cause damage to the system.
INPUT POLARITY CORRECTION
IEEE 802.3cg requires input polarity insensitive PDs to facilitate fool-proof field installation with screw terminals. The EVAL- LTC9111-AZ PD motherboard polarity corrects the two inputs, IN1 and IN2. The LTC9111 drives external MOSFETs for the low-side rectifiers and relies on external Schottky diodes for the high-side rectifiers. Active low-side rectification minimizes power losses and overcomes circuit start-up challenges posed by the constraints in the standard. Footprints for both dual-MOSFET (single package, default option) at Q1, and discrete 3mm × 3mm DFN MOSFETs at Q2 and Q4 (optional), are available on the PCB for the active low-side rectifiers.
SPOE PD CLASS
The LTC9111 SPoE PD class is configured by the CLASSC and CLASSV pins. CLASSV is a binary input, either low by connecting to GND or high by connecting to STBY. CLASSV is tied low for the 24V classes (Class 10 to Class 12), and high for the 54V classes (Class 13 to Class 15). CLASSC is a trinary input, set either low by connecting to GND, high by connecting to STBY, or high impedance by floating the pin. Refer to Table 1 for configuration options and Figure 6 for jumper location.
OVERVOLTAGE PROTECTION FOR 24V PDS
When the LTC9111 is configured for Class 10 to Class 12 (that is, CLASSV pin is tied low), an overvoltage protection feature is enabled to protect downstream elements in the application from exposure to excessive voltage. When the input voltage exceeds VOV (38.5, typ), the gate of the external hot swap MOSFET turns off, regardless of the port state.
SENSE SNUBBER
A snubber between the SNS pins prevents high-frequency ringing when the rectifying diodes are reverse biased during SCCP logic transitions. On the EVAL-LTC9111-AZ motherboard, the P4 jumper connects or disconnects the sense snubber. Set the P4 jumper to CONNECT when using the EVAL-10BT1L-MCS-AZ SPoE shield (Class 10 to Class 14) to connect the sense snubber. Set the P4 jumper to DISCONNECT when using the EVAL-10BT1L-MCS-BZ SPoE shield (Class 15) as the sense snubber is already present on this SPoE shield. Refer to Figure 7 for jumper location.
EVAL-LTC9111-AZ DEMONSTRATION CIRCUIT
STBY SUPPLY
An internal linear regulator produces a nominal 3.5V supply at the STBY pin. It is used to power internal control circuitry. The STBY pin has a capacitance of 2.2μF placed near the pin.
Note that any external load on the STBY pin during classification may discharge the capacitor and cause brownout. There must be no load on the STBY pin during classification.
ON-BOARD MICROCONTROLLER FOR PHY
The EVAL-LTC9111-AZ PD motherboard includes an on-board microcontroller for configuring an Ethernet PHY located on the SPoE shields via the MDIO interface.
Note that the microcontroller is not required for the LTC9111 operation.
The microcontroller is powered from the on-board 3.3V buck regulator and the MDIO interface is isolated on the SPoE shield. Header J7 is used for programming the microcontroller. Switch S1 is used for resetting the microcontroller.
ON-BOARD 3.3V BUCK REGULATOR
The EVAL-LTC9111-AZ PD motherboard has an on-board buck converter that steps the LTC9111 output down to a 3.3V logic rail. This supply powers the SPoE shield and on-board microcontroller. An additional 3.5A load may be connected to the 3.3V/3.5A turret. Refer to Figure 8 for on-board 3.3V buck regulator location.
EXTERNAL SCCP HEADER
An external SCCP circuit may optionally perform classification instead of the LTC9111. The EXT SCCP header (J6) brings out the IN1 and IN2 inputs, as well as the STBY supply and GND. The external SCCP classification circuit may pull IN1 and IN2 to GND. The LTC9111 SCCP pull-down FETs (Q11 and Q12) must be disabled or uninstalled to not interfere with the external SCCP circuit. Refer to the LTC4296-1 SCCP Wiki for more information on the classification protocol.
LAB_OUT CIRCUIT
During inrush, there can be significant transient power dissipation in the external MOSFET. Any load present before inrush is complete increases MOSFET stresses. LAB_OUT− turret is a return path for restive or active loads that are only connected after inrush has completed. The EN pin is held low then rises to 3.4V (typ) after inrush has completed. When EN is high, the LAB_OUT circuit applies 12V to a power MOSFET gate which connects LAB_OUT− to GND. Connect a resistive or active load between OUT+ and LAB_OUT−.
Note that the user must not capacitively load LAB_OUT−.
OPTIONAL HOTSWAP MOSFET PACKAGE
Q13 provides an optional SOT-223 package footprint for the Hotswap MOSFET.
ESD Caution
ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.
Legal Terms and Conditions
By using the evaluation board discussed herein (together with any tools, components documentation or support materials, the “Evaluation Board”), you are agreeing to be bound by the terms and conditions set forth below (“Agreement”) unless you have purchased the Evaluation Board, in which case the Analog Devices Standard Terms and Conditions of Sale shall govern. Do not use the Evaluation Board until you have read and agreed to the Agreement. Your use of the Evaluation Board shall signify your acceptance of the Agreement. This Agreement is made by and between you (“Customer”) and Analog Devices, Inc. (“ADI”), with its principal place of business at One Analog Way, Wilmington, MA 01887-2356, U.S.A. Subject to the terms and conditions of the Agreement, ADI hereby grants to Customer a free, limited, personal, temporary, non-exclusive, non-sublicensable, non-transferable license to use the Evaluation Board FOR EVALUATION PURPOSES ONLY. Customer understands and agrees that the Evaluation Board is provided for the sole and exclusive purpose referenced above, and agrees not to use the Evaluation Board for any other purpose. Furthermore, the license granted is expressly made subject to the following additional limitations: Customer shall not (i) rent, lease, display, sell, transfer, assign, sublicense, or distribute the Evaluation Board; and (ii) permit any Third Party to access the Evaluation Board. As used herein, the term “Third Party” includes any entity other than ADI, Customer, their employees, affiliates and in-house consultants. The Evaluation Board is NOT sold to Customer; all rights not expressly granted herein, including ownership of the Evaluation Board, are reserved by ADI. CONFIDENTIALITY. This Agreement and the Evaluation Board shall all be considered the confidential and proprietary information of ADI. Customer may not disclose or transfer any portion of the Evaluation Board to any other party for any reason. Upon discontinuation of use of the Evaluation Board or termination of this Agreement, Customer agrees to promptly return the Evaluation Board to ADI. ADDITIONAL RESTRICTIONS. Customer may not disassemble, decompile or reverse engineer chips on the Evaluation Board. Customer shall inform ADI of any occurred damages or any modifications or alterations it makes to the Evaluation Board, including but not limited to soldering or any other activity that affects the material content of the Evaluation Board. Modifications to the Evaluation Board must comply with applicable law, including but not limited to the RoHS Directive. TERMINATION. ADI may terminate this Agreement at any time upon giving written notice to Customer. Customer agrees to return to ADI the Evaluation Board at that time. LIMITATION OF LIABILITY. THE EVALUATION BOARD PROVIDED HEREUNDER IS PROVIDED “AS IS” AND ADI MAKES NO WARRANTIES OR REPRESENTATIONS OF ANY KIND WITH RESPECT TO IT. ADI SPECIFICALLY DISCLAIMS ANY REPRESENTATIONS, ENDORSEMENTS, GUARANTEES, OR WARRANTIES, EXPRESS OR IMPLIED, RELATED TO THE EVALUATION BOARD INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY, TITLE, FITNESS FOR A PARTICULAR PURPOSE OR NONINFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS. IN NO EVENT WILL ADI AND ITS LICENSORS BE LIABLE FOR ANY INCIDENTAL, SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES RESULTING FROM CUSTOMER’S POSSESSION OR USE OF THE EVALUATION BOARD, INCLUDING BUT NOT LIMITED TO LOST PROFITS, DELAY COSTS, LABOR COSTS OR LOSS OF GOODWILL. ADI’S TOTAL LIABILITY FROM ANY AND ALL CAUSES SHALL BE LIMITED TO THE AMOUNT OF ONE HUNDRED US DOLLARS ($100.00). EXPORT. Customer agrees that it will not directly or indirectly export the Evaluation Board to another country, and that it will comply with all applicable United States federal laws and regulations relating to exports. GOVERNING LAW. This Agreement shall be governed by and construed in accordance with the substantive laws of the Commonwealth of Massachusetts (excluding conflict of law rules). Any legal action regarding this Agreement will be heard in the state or federal courts having jurisdiction in Suffolk County, Massachusetts, and Customer hereby submits to the personal jurisdiction and venue of such courts. The United Nations Convention on Contracts for the International Sale of Goods shall not apply to this Agreement and is expressly disclaimed. All Analog Devices products contained herein are subject to release and availability.
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Documents / Resources
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