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TPS23881: SCH check Request

HY yang
Expert 1980 points
Part Number: TPS23881
Other Parts Discussed in Thread: TPS23880,

Attached is the schematic diagram of our KMM customer's Poe scheme design provided by Ti. Please help to confirm if there is any problem.

One thing I want to confirm is that the POE driven 200W solution provided by Ti uses the tps23880 + tps2372-4 solution,

We use the combination of tps23881 + tps2372-4. Is this scheme feasible?

Attached is the schematic diagram of tps23881 + tps2372-4. If this kind of plan is feasible, please help to confirm that we are now

Is there any problem with the parameters set, especially the parameters of the auto foot.

PCB2_PD_TI.pdf

PCB2_PSE_TI.pdf

  • 0
    TI__Genius 15685 points

    Hi HY,

    Please see my comments on the PSE schematic:

    1. The Rsense should be 200mohm for each channel(your schematic has 110mohm).
    2. I saw the SCL and SDA are connected to a host, so I assume you have a host in the system to be able to load SRAM code (need 18K memory) once the system is powered up.  Please download MSP430 reference code and refer to the source code for how to load SRAM code through I2C. The latest SRAM code is available on TPS23881 mySure folder. If you don't have access, please request here.
    3. If the 4pair port is designed to support type 4, you have to follow the below polarity (MDI-X and B(S)) to connect the channels to the RJ45 connector. 

    I am notifying PD apps to review your PD schematic. 

    Best regards,

    Penny

  • 0 in reply to Penny Xu
    TI__Mastermind 41760 points

    Hi HY,

    On the PD, there usually is some filtering after the bridge to help with EMI. It looks like you're trying to do a high power solution so EMI considerations are important.

    I know beyond BT app note shows autocls pulled down and it is optional for this application. But if you're not planning to use it, most applications don't use autoclass, then, I recommended using a resistor to VSS and unpopulated to leave it floating with an option to use it if you need to.

    Lastly, TPH,TPL,BT, are typically used in conjunction with a micro controller to tell your load what type PSE is connected. Since this is a nonstandard solution, I guess you don't really need to use it but wanted to let you know how these signals can be used if you wanted your load to process that extra information.