Q: 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]

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?

A: The standalone circuit on page 36, Fig.41, has one missing connection, pin SYSOFF. This seems to be the datasheet mistake.

The spec says about SYSOFF pin:

System Enable Input. Connect SYSOFF high to turn off the FET
  connecting the battery to the system output. When an adapter is
  connected, charging is also disabled. Connect SYSOFF low for normal
  operation. SYSOFF is internally pulled up to VBAT through a large
  resistor (approximately 5 MΩ). Do not leave SYSOFF unconnected to
  ensure proper operation.

SO it looks like the transitor Q2 (see functional diagram section 9.2) is floating, partially open, which causes the voltage to drop.
Connect the SYSOFF to ground for proper operations.
