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BQ25798: chip not entering low power to reach the 17uA

Christian Cortes
Prodigy 30 points
Part Number: BQ25798

Tool/software:

I am wondering how the charging chip is able to get to 17uA of quiescent current. our current config does not have a shipFET and no charger connected. after doing HW investigations on the board, we decided to remove the chip completely and noticed that it was consuming ~180mA which is really high. any input would be appreciated. 

  • 0
    TI__Guru**** 166126 points

    Hi Christian,

    With only battery connected at BAT/BATP and no load at SYS, the charger Iq is shown below and it is tested in production.

    Note that the internal battery FET's body diode from BAT to SYS is always present so if there is a load on SYS it will pull current from the battery.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 30 points

    I misspoke earlier about the 180mA, I meant to say 180uA. We ran a test where we had the BQ populated, battery plugged in (~3.7V), no charger present, and ADC disabled, and we observed that the board was pulling 560uA from the SYS. Then, we removed the BQ chip and shorted BAT to SYS and the board was now pulling 380uA, which is 180uA less. Based on this observation, we concluded that the BQ's quiescent current is ~180uA. Is there a particular register configuration that we need to set in order to hit the lowest sleep consumption of 17uA?

  • 0 in reply to Christian Cortes
    TI__Guru**** 166126 points

    Hi Christian,

    In battery only with ADC disabled (EN_ADC bit =0), the Iq is 24uA max.  If you have a BQ25798EVM, you can confirm but you need to remove the 3.3V pull up voltage jumperJP30.

    Regards,

    Jeff