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BQ77915: Doesn't work properly during charging.

Nicky Lim
Genius 3195 points
Part Number: BQ77915

Hello,

Make a circuit as attached with BQ7791500.

It works well with Discharge but doesn't work well during charging.

3-Cell battery is used and its voltage is 4.1V, 3.8V & 3.6V each.

In charge mode, start charging but stop charging immediately.

Could you check attached schematic and  let me know why stop charging immediately? 

Regards,

Nicky

  • 0
    TI__Expert 7465 points

    Hi Nicky,

    The note in your schematic says that you are using a BQ7791500 with 1.2V under voltage protection and 4.2V overvoltage protection. The BQ7791500 does have 4.2V over voltage protection, but the under voltage threshold is actually 2.9V, not 1.2V. Make sure that none of your voltages are below 2.9V when this issue happens.

    Additionally, the note says that the cell monitor filter has resistor values of 1k Ohm. This is correct. The schematic seems to show 33 Ohms, which is not correct. Please make sure those resistor values are 1k in order to meet the cell balancing requirements.