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bq24190 / Delay time from setting DPDM_EN bit to VBUS_STAT bit reflected

S.Satoshi
Guru 21675 points

Hi All,

Let me ask about DPDM_EN bit and VBUS_STAT bit.

I understand that the DPDM detection is forced when DPDM_EN bit is set, and then VBUS_STAT bit is reflected after detection is completed. And now I'd like to know the delay time from setting DPDM_EN bit to VBUS_STAT bit reflected. It looks like the VBUS_STAT bit is changed after 1 sec from set DPDM_EN. I hope to shorten this delay time as possible.

Best Regards,

Sonoki / Japan Disty

  • 0
    TI__Expert 4285 points

    Hi Sonoki,

    1sec is about right. You cannot shorten the delay, as it is part of detection procedure.

    Best Regards,

    Linhong

  • 0 in reply to Linhong Qin
    Guru 21675 points

    Hi Linhong-san,

    Thank you for your response. I understand that we need to consider 1 sec to complete detection procedure.

    Then I'd like to ask the operation when set DPDM_EN during running auto detection after VBUS presented. I guess following operation at this situation.

    • DPDM_EN will be ignored and the result of auto detection will be effective.
    • Or the auto detection will be interrupted and restart detection by DPDM_EN.

    I have asked the same question in the separated thread as below.

    e2e.ti.com/.../1451940

    Your comment will be appreciated.

    Best Regards,

    Sonoki

  • 0 in reply to S.Satoshi
    TI__Expert 4285 points

    Hi Sonoki,

    The Force detection command is ignored if detection is in progress.

    Best Regards,

    Linhong

  • 0 in reply to Linhong Qin
    Guru 21675 points

    Hi Linhong,

    Our customer checked the status of IINLIM setting (REG00[2:0]) after 1sec DPDM_EN set, but the status was not changed. They have never seen such condition after 1.5sec. So they commented that 1sec is not enough to complete detection procedure. Please confirm your designer the worst case of duration to complete detection procedure.

    Best Regards,

    Sonoki

  • 0 in reply to S.Satoshi
    TI__Expert 4285 points

    Hi Sonoki,

    1sec is actually more than enough. Could you please describe in detail your test procedure, especially on how you measure the delay time? I'd like to check if I can reproduce it here. Thanks.

    Best Regards,

    Linhong

  • 0 in reply to Linhong Qin
    Guru 21675 points

    Hi Linhong,

    They have controlled bq24190EVM via their host controller .

    First, let me explain hardware condition. But I believe it's OK that you connect USB only and change IINLIM via I2C, and then force DPDM.

    • Dual input (AC or USB) is configured by using dual input/single output power mux.
    • Operate from AC only, so VBUS_STAT should be "Unknown" at this point
    • Next connect also USB and then force DPDM detection

    For this evaluation, they have checked delay time with following procedure.

    • Set DPDM_EN
    • Read VBUS_STAT after 1sec

    Customer said that there is possibility that their hardware or software may have problem, so they continue to check their system also. It's appreciated if you will check this operation on your bench, but let me know if your designer commented the 1 sec should be enough.

    Best Regards,

    Sonoki

  • 0 in reply to S.Satoshi
    TI__Expert 4285 points

    Hi Sonoki,

    Typical value by design is 0.5sec, max at 0.75s. if there is hardware connection issue and signal is not detected, DCD will time out at 0.5sec. I would suggest customer get the robust, correct detection result first, then work on timing.

    Best Regards,

    Linhong