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TPS23731: Type 3 class 1-4 25.5W with 5Vout_Suggestion POE part

Ching-Fei Ho
Prodigy 150 points
Part Number: TPS23731
Other Parts Discussed in Thread: LM5072, TPS23754, TPS23751, , TLV431, TPS23734, TPS23756, TPS23752

Tool/software:

Hi Team,

I have a project that need to support type 3 class 1-4 25.5W with 5Vout, and there would be both input power of ethernet network port and 48VDC adapter.

Does TI have any suggestion POE part and the comparison table to let me take reference?

Thanks.


 

  • 0
    TI__Mastermind 32021 points

    Hi Ching-Fei,

    TPS23731EVM (https://www.ti.com/tool/TPS23731EVM-095) should be a suitable reference design using PSR for your case. Attachment could also be a suitable design but using SSR. Let me know if you need PCB file and I can share via email.

    TPS23731+Tele+SSR Flyback+48&12V_adapter 5V_output Class4_Sch.PDF

    Below table may help

    Differentiated feature

    Description

    LM5072

    TPS23754/6

    TPS23751/2

    TPS23731/4

    IEEE Standard*

    IEEE Ethernet Standard that the device compliant

    IEEE 802.3 af

    IEEE 802.3 at, af

    IEEE 802.3 at, af

    IEEE 802.3 bt, at, af

    Integrated Hotswap Rating**

    Voltage rating normally implies ESD/inrush ruggedness. On resistance implies the power loss. 

    100-V, 0.7-Ω

    100-V, 0.5-Ω

    100-V, 0.5-Ω

    100-V, 0.3-Ω

    Primary-side Regulation (PSR)***

    Sensing the Vout by the auxiliary winding at the primary side to do the feedback. No need for external optocoupler and error amplifier.

    Need 1 x TLV431 + 1 x optocoupler for SSR

    Need 1 x TLV431 + 1 x optocoupler for SSR

    Need 1 x TLV431 + 1 x optocoupler for SSR

    Yes

    Gate Driver Output**

    Number of gate driver outputs. Normally an additional gate output allows driving an active-clamping FET.

    1

    2

    1

    TPS23731: 1

    TPS23734: 2

    Frequency Dithering**

    Reduces the narrowband EMI by spreading out the noise spectrum. Help to pass the EMI test.

    No

    No

    No

    Yes

    Programable

    UVLO*

    Adjustable hotswap to allow low voltage (<36V) passive injector connection.

    Yes

    Yes

    No

    No

    Programable

    Inrush limiting*

    Allow programable current limitation. Not needed in most of PoE application now.

    Yes

    No

    No

    No

    Primary Side Adapter Before PD*

    Compatible with low voltage dc adapters.

    > 12V

    TPS23756 > 15V

    TPS23754 >  18V

    No

    No

    Primary Side Adapter Priority After PD**

    Set adapter input a higher priority and disable the PD negotiation with PSE.

    Yes

    TPS23756 > 12V

    TPS23754 >  18V

    > 18V

    > 18V

    DC/DC Controller Soft Stop**

    The soft-stop feature minimizes stress on switching/sync FET(s) in forward. And avoid natural oscillation in flyback with sync FET.

    No

    No

    No

    Yes

    Auto Maintain Power Signature**

    PD will generate pulse current to maintain power signature. So PSE won’t turn off this channel when the PD is in ultra low power mode.

    No

    No

    TPS23752: only at sleep mode

    TPS23751: No

    Yes

    Variable Frequency Operation*

    Reduce switching frequency at low output power conditions to improve efficiency

    No

    No

    Yes

    No

    Sleep Mode*

    Keep PD-PSE connection but turn of the DC/DC controller to a low power sleep mode

    No

    No

    TPS23752: Yes

    TPS23751: No

    No

    Hotswap Foldback Protection**

    Keep the internal hotswap FET working in a safe operation area as hiccup mode when over load / short circuit after the hotswap FET.

    No

    Yes

    Yes

    Yes

     Best regards,

    Diang