This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TIDA-010261: Bridge rectifier inquiry

Part Number: TIDA-010261

Tool/software:

Hello,

I have a customer evaluating the TIDA-010261 SPE/PODL reference design for a new project and we have a question regarding the power/data interface that I'm hoping you can help to provide guidance on. See below!

Snipped below is the schematic section showing the power/data interface, I’m trying to understand the bridge rectification formed with D18,D19,D21,D22. If D20(TVS) was a unidirectional device, I would understand the need for rectification. Am I missing something? Couldn’t D20 simply be placed across Power/Data_P and Power/Data_N?

-Matt

  • Hi Matt,

    Can you point your customer also to the application note on the PoDL PD: https://www.ti.com/lit/an/snvaa25a/snvaa25a.pdf

    This explains the implementation in more details, and might already address your customers question.

    I will also check with our team and come back to you later this week. 

    Regards,

     Thomas

  • The diode D20 is a TVS diode, to protect against high transient voltages. As this is a rather high capacitance, it might degrade the signal quality and with this violate the specification and reduce the cable reach.

    In order to reduce this capacitive effect at low voltages, it is placed inside of this diode bridge configuration, at the low signal voltages, the capacitance of the diode will not be seen from the outside, but at high voltage transients it can still do its job.

  • Thank you so much for the detailed reply Steffen! I'll pass this info along to the customer and will have them comment back on this thread directly with any follow-up questions they may have on this.

    Another part of this design we had a question on was regarding the bridge formed by D1,D5,D6, and D7. Assuming SCCP/PWR is the incoming source for DOPL, it is connected to the anodes of D1&D6 so there is not a path for current to flow. Does this seem correct? Any explanation on this circuit implementation would be much appreciated! 

    -Matt

  • Hi Matt,

    the PoDL PSE is connected at the right side of the screenshot, so independed of the polarity here, the GND label will be the return path and the SCCP/PWR will provide the voltage. This is basically a classical Greatz bridge, as you know it from AC/DC power supplies.

    The D+ and D- ports are connected to a circuit sensing the SCCP communication.

    Best regards,

    Steffen