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BQ25890: Different ADC mode leak current

Lillian Liu(SH)
Expert 4620 points
Part Number: BQ25890

Hi team,

My customer sets REG02 bit6: 0(one shot ADC), the leak current of VBAT is 190uA and sets REG02 bit6: 1(Start 1s Continuous ), the leak current of VBAT is 340uA.

Please help to identify the leak current in the different mode of ADC with BQ25890EVM or can you help to give a report about it ?

Thanks.

  • 0
    TI__Mastermind 31100 points

    Hi Lillian, 

    Can you confirm if the device is in battery only mode (i.e. no input adapter connected to VBUS) when your customer measures the VBAT quiescent current? 

    Assuming the BQ25890 is in battery only mode, leakage from BAT is expected to be higher for 1s continuous ADC compared to one shot ADC. This is due to ADC requiring more power to provide measurements continuously. Similarly, if the ADC is not active you can expect the quiescent current to be even lower.  

    Best Regards,

    Garrett

  • 0 in reply to Garrett Kreger
    TI__Expert 4620 points

    Garrett, thanks! We have known leakage from BAT is higher for 1s continuous ADC mode , and my customer want to know the different ADC modes' contribution to quiescent current, ( it means the quiescent current value that only ADC mode caused).And can you provide the measured data in BQ25890HEVM?

  • +1 in reply to Lillian Liu(SH)
    TI__Mastermind 31100 points

    Hi Lillian, 

    Please see my comments below on battery quiescent current in different modes. These measurements have been taken on a BQ25890HEVM with Vbat = 4.2V as the only power source for the device. 

    When ADC is not enabled and BATFET turned off BAT Iq = 14.6 uA. When ADC is not enabled and BATFET is turned on BAT Iq = 39.9 uA. These measurements are both in line with the parameters listed in the electrical characteristics section of the datasheet, which I have also inserted below. 

    When ADC is enabled and in 1s continuous mode BAT Iq = 243.3 uA. Therefore Iq due to ADC is approx. 203.4 uA. 

    When ADC is enabled and in one shot mode BAT Iq = 243.5 uA. Therefore Iq due to ADC is approx. 203.6 uA. 

    Based on my test setup when you attempt to read the active ADC the Iq draw is the same no matter if in 1s continuous mode or one shot mode. If your customer reads updates from the ADC at a slower rate then every 1 second then the average Iq draw will be lower in one shot mode compared to 1s continuous. If your customer is reading updates from the ADC approximately every 1 second then the Iq will be the same (~203.5 uA) no matter what ADC mode they are in. 

    Best Regards,

    Garrett  

  • 0 in reply to Garrett Kreger
    TI__Expert 4620 points

    Hi Garrett, 

    Thanks for your reply.

    Best Regards

    Lillian