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TPS23861 802.3af mode

burak balkuv
Intellectual 620 points
Other Parts Discussed in Thread: TPS23861

What is the recommended method to configure the TPS23861 in 802.3af mode only ( ~15W only)?

Can it be configured without a host CPU?

  • 0
    TI__Genius 15685 points

    Hi Burak,

    The power level of PSE's oytput really depends on what type of PD is connected to the PSE. If the PD is Type 1(13Wreceived), the PSE only provides 15W(sourced). If the PD is Type 2(25.5W received), PSE would provide 30W(sorced). 

    I am trying to understand your application.

    1. Do you have the control on the PD side that you know there is no possibility that Type 2 PD will be connected to PSE?
    2. Or you don't have the control on the PD side and you want to limit the power from PSE even if a Type 2 PD is connected to the PSE?

    If you are under situation 1, you don't need to use host to limit the power. PSE will automatically set the power limit when Type 1 PD is detected.

    If you are under situation 2, you need a host to change the ICUT to limit the port output power.

    Best regards,

    Penny

  • 0 in reply to Penny Xu
    Intellectual 620 points
    Thank you for your quick response
    My application is similar to 2)
    -If the Per channel current exceeds 350ma I need to shut it down as my supply does not have the capacity to sustain such loading.
    -Can you point me to what needs to change to limit the load to POE levels only ( ~350ma)
  • 0 in reply to burak balkuv
    TI__Genius 15685 points
    Hi Burak，

    You will need to configure register 0x2A,0x2B(374mA) and 0x40(1X curve). Additionally, if you don't want the load to pull more than 15W from PSE, you had better to disable the two event classification in register 0x21 as well. Once the PD only receives one event classification, it will tell the load to pull only Type 1 power.

    Best regards,
    Penny