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BQ79616-Q1: Much too high shutdown current for BQ79616

Christian Campestrini
Prodigy 150 points
Part Number: BQ79616-Q1

Hello,

if I connect the BMS on HV and LV side on but don't wake up the BQ, the shutdown current supply is around 20µA. If I switch on the LV side, leading to a wake up and configuration of the BQ the shutdown current increases to 1.2mA after shutting down. The shutdown is performed by stopping communcation and switchig of LDOIN. Why do we have such a high shutdown current?

Thanks for your help.

BR

Christian

  • 0
    Prodigy 150 points

    I have to correct me: we switch off the power of the input of the LDO. In the described shutdown case (with the high shutdown current), LDOIN, CVDD are 5.5V. NPNB is 6.2V. in the first case NPNB is only 4.95V. Why?

  • 0 in reply to Christian Campestrini
    TI__Expert 8605 points

    Hi Christian,

    Did you enable TSREF after waking up BQ?

  • 0 in reply to Wayne Liu
    Prodigy 85 points

    Me thinks (not gospel):

    1. When not configured NPNB maintains a lower voltage.  Once configured it tries to maintain a higher one.

    2. The TX line is always high (or at least after configuration).

    If using the UART is the RX holding low keeping the BQ chip in POR?

    If using the UART is your TX line backfeeding through ESD diodes?

    Is the NPNB signal backfeeding?

    At this point if you are removing the LDOIN by turning off the transistor collector supply I don't think that really works to put the BQ chip into it's lowest current draw state.

    Good luck!

    ~J