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TPS65987D: PD response time

Joshua Kim
Intellectual 590 points
Part Number: TPS65987D


Dear,

My sink only USB powered TPS6597D device works well. However, I perceive an odd.

Power negotiation time is too slow over 3 sec for a kind of charger (A); from connecting the USB plug to getting the 15V output; while another model B charger gets less than 1 sec.

Model A charger Model B charger
3.5 sec 0.6 sec

Of course, I argued the model A charger manufacturer. But they claimed their product is no problem with another battery-powered device like this photo.

Would you advise me how to speed up the PD response time with the (A) charger?

  • 0
    TI__Expert 6430 points
    Hi Jeong,

    I see that the issue lies with the power adaptor A. It's providing around 2.5V to start with, which is wrong.

    A PD source should provide less than 800mv upon connection untill Rp and Rd are detected.

    If you see the waveform of adaptor A then you'll find that the VBUS voltage is discharging slowly after the connection and the negotiation happens quickly once it reaches around 800mV.

    Thanks,
    Rahul