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TPS23880: PD sense resistor

Penn Zhang
Intellectual 1180 points
Part Number: TPS23880
Other Parts Discussed in Thread: TPS2373

Hello,

According to the datasheet,  PD Raccept  19~26.5Kohme,  Rreject >33K or <15K , if R is between 15K~19K or 26.5K ~ 33K, will PSE deliver power to PD side?

Thanks.

  • 0
    TI__Intellectual 1180 points

    + 1 question

    How does the TPS23880 detect PD impedance and what is the principle?

    There is a MOS bridge between the tps2373-4 PD cand the PSE TPS23880. When the PSE detects the PD resistance, the output is only about 10V.
    The MOS has not been turned on. The parasitic diode is turned on first. The diode voltage drop is about 0.6V, so the total line voltage drop is ~1.3V, and it is less than 8.7V to the TPS2373 terminal. Will this voltage drop cause the PSE chip Can't you measure the impedance of the PD chip?
    With or without mos bridge, how much does the detection resistance of the PD chip differ, and will the deviation exceed 20%?

    Thanks.

  • 0 in reply to Penn Zhang
    TI__Genius 15685 points

    Please check TPS23880 datasheet for detection mechanism. I am checking with firmware developer on how we deal with the resistance range in your original post and will get back to you asap. Thanks. 

    Best regards,

    Penny

  • 0 in reply to Penny Xu
    TI__Genius 15685 points

    Penn,

    I have replied to you through email, so I am closing this thread. Thanks.

    Best regards,

    Penny