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]
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?