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BQ24005 issue

Daryl F
Prodigy 10 points
Other Parts Discussed in Thread: BQ24005, BQ24004

I want to use the BQ24005 to design a charge circuit for a 2 Cell Li-ion battery: 8.4V 1200mAh.

I read in the BQ24004/5/6 user guide (SLUU110A) on page 1-2 under table 1-1 the following:

"Vi for a 2-cell, should not exceed 9.1 VDC for the 1A charge current..."

Does this mean the supply voltage on pins 2 and 3 (IN) has to be 9.1V???

What happens if the voltage is 9.0V or 9.2V???

  • 0
    TI__Prodigy 720 points

    For linear charger, the power loss is proportional to charge current and input-output voltage difference.

    So for input voltage, above 9.1V may cause IC too hot to be damaged.

    That's the reason for 9.1V 1A charging current.

    Power loss worst case, 2cell battery 6V(3V/cell for fast charging), input 9V, 9-6=3V, 1A gives 3W loss. Temperature rise will be 93C according to datasheet thermal impedance.