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BQ24296M: BQ24296M can not start on load

Skate Lu
Intellectual 870 points
Part Number: BQ24296M

I have a new design with BQ24296M. And I have a problem that BQ24296M can not start on load. No battery connect BQ24296M.

Load capacitor is 120 uF.

The load capacitor  go beyond the limit yes or no?

Can someone give me some advice?

Thanks a lot !

  • 0
    TI__Expert 8230 points

    Hello Skate,

    The SYS capacitance might be too high and it's affecting the converter start up with no battery and load.

    If no battery is present, the SYS voltage will most likely be less than than 2.2V. When SYS<2.2V, the input current limit is clamped to 100mA during start up. Once the SYS voltage increases pass 2.2V, the actual input current limit is used and the device can continue with normal operation. Section 8.3.1.4 of the datasheet goes over this in more detail.

    If the device is in soft-start with a 100mA current limit and there's a load on SYS, the load will prevent the SYS voltage from coming up due to the fact the input can't provide the power required. 

    You can try reducing your SYS load or capacitance and see if it helps with start-up.