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BQ24075: Charge current does not get to expected levels

abraham maclean
Prodigy 20 points
Part Number: BQ24075
Other Parts Discussed in Thread: BQ27510

Using a Lithium Ion battery and the BQ24075 battery charger, when USB power is supplied, the charging current does not get to the expected level. I have the EN1 and EN2 pins configured for 500mA charging limit, SYSOFF and CE are driven low to enable charging. 

When a charger is plugged in, the charge current is ~90mA with 30mA system draw. Following the battery charging flow diagram in the datasheet, the charger gets stuck waiting for I(BAT) < I(TERM) and T(FASTCHARGE) elapses, causing #CHG to flash. The battery is being charged, but at a much slower rate than expected.

I have tested with different batteries at different voltages(3.0V - 4.0V), different boards (using a custom board, schematic below), different USB sources, and different EN1 and EN2 configurations. All yield the same results.

This is being used in conjunction with the BQ27510 fuel gauge, but I have ruled that out.

  • 0
    TI__Mastermind 21590 points
    Hello Abraham,
    Looking at your schematic, you have both EN1 and EN2 connected to ground. This will always set that maximum input current to 100mA regardless of what the ISET is set to. Try setting EN2 high and check if you still have his issue

    Regards,
    Raheem