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BQ24040: BQ24040 pre-charging

user5006961
Intellectual 805 points
Part Number: BQ24040

I found when I was in the test charge is not stable, I set of CC is 540 mA, and PRETERM feet I'm folt, at this time of charging should be 20% of Ichg.

BUut in fact, I use a load meter to simulate the battery, directly to the load transferred to the 2.5 V, the charging current is more than 20% and unstable, is about 120-140 ma.

Only gradually will load from high voltage to 2.5 V is 20% of the charging current.

Is that normal?

  • 0
    TI__Guru* 75936 points
    Hello
    They BQ24040 will transition from pre-charge to fast charge current at 2.5V. Pre-charge current and termination current can be set with PRETERM resistor and 20% pre-charge value is common.
    If you are seeing instability in the transition point or current try adding a large capacitor, 100uF to simulate the battery in your test set up.
    Other things to look at would be input voltage and filtering, possible noise as current tries to increase.