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TPS2384: About PD detection issue

Yang Ken
Intellectual 500 points
Part Number: TPS2384
Other Parts Discussed in Thread: TPS23861, TPS2388

Hi Sir,

Our client meets the detection issue of PSE controller TPS2384 and could be duplicated in TPS2384EVM.

And they found the Cgood cap(0.22uF) of EVM is over the 802.3at specification max.(0.15uF), and remove the Cgood(C1A1) cap then test it again the result is work normally.

So there are two questions need your help:

1. What TI consideration to design 0.22uF in Cgood(C1A1)?

2. Is there any compatibility issue related to TPS2384?

Thanks

Regards,

Ken

  • 0
    TI__Genius 15655 points
    Hi Ken,

    0.15uF is the max cap in parallel with detection resistor during detection(table 33-5). On the PSE side, the max output cap is 0.52uF during detection(33-11). What's the PD input cap in your test? TPS2384 is a IEEE802.3af compliant device and TPS2384 uses forced voltage to do detection and this is a little sensitive to PD input cap as it takes some time to charge the cap. Our newer device TPS23861 and TPS2388 use forced current to do detection which is more robust when the port cap is a little higher. Thanks.

    Best regards,
    Penny
  • 0 in reply to Penny Xu
    Intellectual 500 points

    Hi Penny,

    Thanks for you promptly support and reply.

    Regards,

    Ken