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replaced "charge protection" with "charger"
Ale..chenski
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Load causes voltage collapse. Why?

I have a circuit where a typical 3.7V LiPo battery supplies power through a bq24074 Charger IC, which should in theory short that voltage straight to the output of the charge-protect circuit, which then can be attached to a load. For a load, I'm having an electronic load drain constant current of 200mA. The flow is as I described:

[LiPo] ---(Vbatt)---> [Charge IC] ---(Vload)---> [Electronic load]

Voltage is collapsing when load is attached

When the load is turned on (draws 200mA), the battery voltage remains relatively unphased, but the voltage between the Charger IC and the Electronic load drops to 1.7V from 4.0V. I followed the application schematic from the datasheet almost exactly, only changing resistors that control charge current rates.

The application I have for this only draws around 15-25mA, and at those draws the voltage collapse is much smaller so there's no urgency in solving this. That said, in the future I want to implement applications that have infrequent large spikes in current consumption, so it begs the questions:

  • In the situation I described, why might the load be causing the voltage to collapse?
  • (and bonus question for curiosity's sake, since google wasn't helpful:) In general, why might a load cause voltages to collapse?