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TPS23755: POE Questions and EVM Source Schematic Files

Scott Walker
Prodigy 10 points
Part Number: TPS23755
Other Parts Discussed in Thread: , TPS23758

I am looking at the TPS23755 as a POE solution and have several questions. I've also included a list of the requirements.

Requirements:
- Powered Device (PD)
- 802.3at Type 1
- 13Watt Support
- DC-DC converter with either 12V output of 3.3V output.
- Support for Gigabit Ethernet. Must support power on all 4 twisted pairs.
- Space and cost requirements are an important aspect of the design.

Questions:
- I noticed that the DC-DC converter EVM (TPS23755EVM-894) is isolated. Is this necessary in this POE application? If not, how would the EVM circuit change and what are the risks?
- How can I go about obtaining the source schematic files for the EVM? Preferably DxDesigner. If not available, send source of any available design tool.
- Are there any similar devices to the TPS23755 that supports 3.3V output on the DC-DC side?
- Would TI be able to review the schematics and layout?

  • 0
    TI__Mastermind 20211 points

    Hi Scott,

    Thanks for reaching out.

    - I noticed that the DC-DC converter EVM (TPS23755EVM-894) is isolated. Is this necessary in this POE application? If not, how would the EVM circuit change and what are the risks?

    The isolation is required by the 802.3 standard.


    - How can I go about obtaining the source schematic files for the EVM? Preferably DxDesigner. If not available, send source of any available design tool.

    I will reach out to you via email.
    - Are there any similar devices to the TPS23755 that supports 3.3V output on the DC-DC side?

    TPS23758 is similar to TPS23755 but support sync FET instead of diode rectification. At 3.3-V and >3-A output, the sync FET has better efficiency than diode rectification. You can find the 5-V EVM in https://www.ti.com/tool/TPS23758EVM-080 and modify it to 3.3-V by adjusting the Vout regulation feedback loop, transformer, and other components ratings.
    - Would TI be able to review the schematics and layout?

    Yes, we can help on schematic and layout review. 

    Best regards,

    Diang