Hi,
I recently got one of my PCBs back from JLCPCB which has a 3.3V microcontroller, a 5V step-up converter (for some sensors) and a 3.3V regulator. It's designed to be operated via a 3.7V < 3000mAh battery LiPo pouch cell. There is no charging circuitry on board.
This is the first time I've made a battery circuit. All parts are from lcsc.com.
ISSUE: On plugging in battery, 3.3V rail doesn't start up. In this problematic state, OD of the DW01-G is at -3.617V and increasing by 1mV every second almost (becoming more positive). OC at 0.247V constant. (Battery at 3.88V). 3.3V rail at 0V.
What I have noticed:If I short OD and CS of the DW01+G circuit - everything works - 5V and 3.3V rails both come online. But I have to do this everytime battery is plugged in.
I also noticed that once the circuit is in a good state with stable rails, if I remove the battery and plug it back in again, the 3.3V rail shows approx. 580mV failing rapidly.
I have tried replacing the DW01+G twice - same issue. I tested the FS8205 with a multimeter using online guides - seems just fine in terms of Rons, etc.
I have also tried what is recommended in the DW01+G datasheet which is to short the CSS and VSS pins to get it out of shipping/transport mode.
I also tried replacing the resistor connected to CS with a 2k instead of a 1k (I saw GreatScott did this)
What is causing this? Why do I keep having to short the OD and CS pins?


Thanks!
DATASHEETS:
DW01-G :
https://www.ic-fortune.com/upload/Download/DW01-G-DS-10_EN.pdfFS8205:
https://www.ic-fortune.com/upload/Download/FS8205-DS-19_EN.pdf