SLVAF74 July   2021 TPS2372 , TPS2373 , TPS23730 , TPS23731 , TPS23734 , TPS2375 , TPS2375-1 , TPS23750 , TPS23751 , TPS23752 , TPS23753A , TPS23754 , TPS23754-1 , TPS23755 , TPS23756 , TPS23757 , TPS23758 , TPS2376 , TPS2376-H , TPS2377 , TPS2377-1 , TPS23770 , TPS2378 , TPS2379

 

  1.   Trademarks
  2. 1Introduction
  3. 2Preparation and Measurement Techniques
    1. 2.1 Important PoE Signals
    2. 2.2 Lab Equipment
    3. 2.3 Measurement Techniques
    4. 2.4 Board Preparation
  4. 3Narrowing Down the Problem Area
    1. 3.1 Schematic Areas
    2. 3.2 Narrowing Down the Area On Board
  5. 4Common Issues
  6. 5Conclusion

2 Preparation and Measurement Techniques

Part of the current TI strategy is to provide working reference designs that can be copied. The first recommendation is to find the closest reference design possible to the design being worked on. Look for the same IC, the same topology (for example, synchronous flyback), and the same output voltage and power level. If there is not a close design, contact the PoE applications engineer through E2E for an internal search. Next, evaluate any parts that are different, whether it be a transformer, a MOSFET, a resistor size, and so forth. Question why the part is different. List all the reasons how these parts are different (for example, different gate capacitance, different reverse recovery time, different voltage rating, different package size). These may be the first clues to why the design is experiencing problems, but the TI reference design is not. Review the PoE PD Schematic Review Guidelines application report for component variations.