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BQ77915: Queries about quiescent current

Genius 14319 points
Part Number: BQ77915

Hi Experts,

We have queries about this design:

1) I have measured the voltage across R1 and found it is around 22.5 mV. I have the R1 of 1k and 0.5% accuracy. So the current is 22.5 uA and seems to be far from 8 uA from the datasheet. Might there be other reasons of this current?

2) When I connect the B+ to the IC, the current is 8.8 uA the first 5 seconds. After that the current goes up to 23 uA. This might help you to find out the problem.

3) Why does the current not change when I remove the R9 ?

Thanks ahead on your assistance.

Regards,
Archie A.

  • Hi Archie,

    1. It's hard to say if this is expected or not. The test conditions that got the 8uA typ spec are 20V VDD and 4V cells in a 5s configuration. It may be that a 3s configuration draws a larger supply current, or different VDD/cell voltages draw a larger current.

    2. Does this correspond with the FETs turning on? It may be that the FET drivers are drawing this extra current.

    3. This is likely because balancing is not active either way due to the cells already being balanced enough.

    Regards,

    Max Verboncoeur