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TPS23881: Measure Power Consumption with TPS23881

Part Number: TPS23881
Other Parts Discussed in Thread: TPS2373

Tool/software:

Good day, community,

I have successfully connected a device using the demo code in automatic mode, configured for 4-pair operation. As shown in the image, both ports used in 4-pair mode are being measured:

  • Is it possible to combine both values and treat them as a single port? Or are the measurements taken independently for each port?
  • Can power measurements be obtained from the ports?
  • While in automatic mode, which I am currently using for testing, is it possible to trigger an interrupt and turn off a port for a specific amount of time, or does this require switching to semi-automatic mode?

Best regards,
Jesus

  • Hi Jesus,

    Thanks for reaching out! Sorry that PoE team is quite busy recently. I will try to get back to you in 5 business days.

    Best regards,

    Diang

  • Hi Jesus,

    Thanks for your patience!

    • Is it possible to combine both values and treat them as a single port? Or are the measurements taken independently for each port?

    - The voltage and current registers are for each channel. Four pairs use 2 channels so you will see two values. You may need to use a MCU (like MSP430 or MPSM0) to add both channel's values.

    • Can power measurements be obtained from the ports?

    - You can check register 54h for power measurement

    • While in automatic mode, which I am currently using for testing, is it possible to trigger an interrupt and turn off a port for a specific amount of time, or does this require switching to semi-automatic mode?

    - If there is some issues (like Pcut, disconnection...) in the turned on port, the port will be turned off and re-handshake is needed. In manual mode, you can interrupt the port with more flexibility by writing though I2C.   

    Best regards,

    Diang

  • Hello Diang Xing,
    Thank you for your responses. My main goal is to control the powering on and off of the ports, specifically to turn off a port for a period of time and then turn it back on. For now, I just need to progress to that point and test its functionality. If you could give me any advice or suggest any changes to make in the semi-automatic demo code, I would be very grateful.

    Best regards,
    Jesus

  • Hi Jesus,

    Thanks for update. I will get back to you in 5 business days.

    Best regards,

    Diang

  • Hi Jesus,

    Since you can use I2C. You can try below actions to turn on/off the port

    To turn on the port:

    Write 12h as 11 auto mode. Then the port with valid PD should be turned on

    To turn off the port:

    Write 19h with POFF = 1, PWON = 0

    Return on the port:

    Write 19h with POFF = 0, PWON = 1

    Best regards,

    Diang

  • Hi Diang Xing,

    I was able to turn off a specific port in semi-automatic mode using the function tps_SetDevicePowerOff(). To re-enable the port after a set period, is it necessary to perform classification again, or could I simply use the tps_SetDevicePowerOn() function without reclassification? What would be the correct procedure if I want to turn off a specific port for a user-defined time and then turn it back on so that the device connected to the port becomes operational again?


    Best regards,

    Jesus

  • Hi Jesus, 

    Diang is currently out of office and will return Nov 12th, apologies for any inconvenience. 

    Thanks and Regards,
    Raymond Lin

  • Hi Jesus,

    Thanks for your patience. It is recommended to turn on the port after detection + classification if you do not an immediate action. This is a safer way than direct turn-on. Meanwhile, most of PD has PSE-PD handshake indication functions (for example, TPH/TPL/BT pins in TPS2373 PD), and these pins need the classification process to make the indicators correct. 

    Best regards,

    Diang