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TPS23751: function check

Julian Chen
Expert 2550 points
Part Number: TPS23751
Other Parts Discussed in Thread: PMP21103

Dear E2E member,

1. Could you let us know how to choose the Optocouplers?

2. After I confirm the Optocouplers SPEC, Does have any data or excile file can simulate the bode plot?

3. Datasheet describe that how to choose (culculate) the RS, could you let us know how about CS and RCS? 

 

4. In our design, we will use a diode to forced operation from either of the power sources. (Please refer the picture as below)

But if we want to save the area and remove the diode (D11) and short it,  Does it have any side effect?

5. If we want to design the hitless PoE solution, does TI have reference design? 

  • 0
    TI__Intellectual 1695 points
    Hi Julian,

    Thanks for your questions.
    For your question 1&2, the optocouplers used in control feedback network is a linear one, the main parameter is the CTR, IF and IC max current and isolation working voltage, you can choose to according to your system. Usually the CTR is around 100%, max current is 50mA and input-output isolation voltage is 5000VACrms minimum.

    For your question 3, please refer to the app note for detail. There is a particular design procedure for flyback.
    www.ti.com/.../slva305c.pdf

    For your question 4, APD function is based on the ARTN, not the GND_PoE. You can't configure it like this. Please refer to our EVM design.
    If you want to use 24V adapter, you can only use ORing option 2, please see detail in the app note below.
    www.ti.com/.../slva306a.pdf
    And the diode is necessary because you can't connect 48V and 24V together.

    For your question 5, we have hitless reference designs but they haven't been released yet. What kind of hitless design do you want?

    Thank you
    Best Regards
    Jack Chen
  • 0 in reply to Jack CCY
    Expert 2550 points
    Dear Jack,

    Thanks for your reply.
    About hitless solution, I find PMP21103.
  • 0 in reply to Julian Chen
    TI__Expert 5615 points
    Julian, Do you think this reference design will meet your needs? We have other "hitless failover" designs in various stages of concept, work, and validation work that we could share under an NDA.
  • 0 in reply to Thomas Lewis
    TI__Expert 5615 points
    Julian, I wanted to check in as we have not heard back from you in a week.

    Please let us know if there is anything else we can do to assist...otherwise, we are going to assume this thread is resolved.

    Thank you for your interest in PoE products from TI,