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TPS23881: PoH on TPS23881

AlexB38
Prodigy 230 points
Part Number: TPS23881

Hi,

One of our customers is using a PoH camera (BOSCH MIC-7130-PW4) which is class 4 on our TPS23881.

The camera works but it does not allow us to activate its IR and light features which consume more than 30W of power. I know the TPS23881 we are using is not designed to provide more than 30W on a class 4, but is there any way to make it work in PoH allowing it to provide up to 60W?

I saw on another forum that the solution to enable PoH can sometimes be done via LLDP but our system does not support this protocol.

Thanks in advance for your help.

Alex

  • 0
    TI__Genius 15685 points

    Hi Alex,

    Please review the training videos here:https://training.ti.com/tps23880-working-noncompliant-high-power-pds-upoe-poe-and-poh

    The LLDP is done through PHY devices, not PoE devices. Once the LLDP is done, the host can change the PCUT value (2Ah and 2Bh register) to the PSE port to increase the power limit to 60W. 

    If the PD doesn't support LLDP and the host knows the connected PD needs 60W, you can also use the same approach to increase the power limit. Thanks. 

    Best regards,

    Penny

  • 0 in reply to Penny Xu
    Prodigy 230 points

    Hi Penny,

    I saw this video but I couldn't find a solution for my case. I have already tried to change the limit of PCUT by the registers 0x2A and 0x2B but it doesn't work completely. As I said in my first post, the camera seems to work but on the web page we have a message that says there is an error with the light function....

    We also tried connecting our TPS23881 to a PoH PD (PoE splitter from PLANET) which is classified as a class 4 equipment. We added a resistor load to draw 60W and it seems to work... Why does it work with this PoE splitter but not with the camera lighting function... ?

    Here, our configuration:

    0x1E, 0x1F, 0x20, 0x21 => set 0xFF

    0x40 => set 0xFF

    0x50 => set 0x00

    0x12 => 0x0F (auto mode) (another try; 0xAA (semiauto))

    Any solution?

    Thanks

    Alex

  • 0 in reply to AlexB38
    TI__Genius 15685 points

    Hi Alex,

    Semi auto mode is preferred for noncompliant use cases. When you see the port can't deliver 60W, can you read the registers fault event registers(0x06,0x08,0x0A)? What your setting of 0x29 register? Can you also share your schematic? Thanks.

    Best regards,

    Penny

  • 0 in reply to Penny Xu
    Prodigy 230 points

    Hi Penny,

    Please find below, a dump from TPS23881 registers without power limitation:

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    [0x00] 0x00
    [0x01] 0x80
    [0x02] 0x00
    [0x03] 0x00
    [0x04] 0x00
    [0x05] 0x00
    [0x06] 0x00
    [0x07] 0x00
    [0x08] 0x00
    [0x09] 0x00
    [0x0A] 0x00
    [0x0B] 0x00
    [0x0C] 0x44
    [0x0D] 0x44
    [0x0E] 0x00
    [0x0F] 0x00
    [0x10] 0x33
    [0x11] 0x00
    [0x12] 0x0F
    [0x13] 0x03
    [0x14] 0x33
    XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

    Here, a capture of the schematic:

    Thanks for help.

    Regards,

    Alex

  • 0 in reply to AlexB38
    TI__Genius 15685 points

    Hi Alex,

    Looks like the SRAM SW is not loaded into the TPS23881. Can you please follow the steps in this app note and load the FW before you configure the device? Since your application is a noncompliant approach, I would recommend you using semi auto mode(first power up the port at 30W, once the port is on, adjust 4P PCUT in register 0x2A and 0x2B). Thanks.