Other Parts Discussed in Thread: BQ2980, BQ27426
Tool/software:
Dear all,
I am currently designing an application which must be powered by a single cell LiPo battery. Charging should be managed by BQ25303 IC. I wanted to add a battery protection IC and utilized the BQ29800RTER. After assembling the design I noticed that the BQ2980 does not transition from POR to NORMAL mode. My explanation is that the BQ2980 starts up and disables the CHG and DSG FETs. This prohibits the BQ25303 to get a proper reading of the battery voltage. Therefore the BQ25303 assumes the battery is not present and delivers 3.1V on the SW pin. As I am using a fully charged battery the condition for enabling NORMAL mode on the bq2980 is not met. You can find the schematic attached below.
So there are some questions:
- If I use a depleted battery with a voltage below 3.1V, will the BQ2980 enable DSG and CHG FETs?
- How could one change the design to enable BQ2980 NORMAL mode when the plugged in battery is fully charged? I would like to have this done automatically if possible.
- Since we are on the topic I suspect the BQ27426 will not be of any use to enable the CHG and DSG FETs via the CTR pin, as it is also separated from the battery?
I am also open for any suggestion on how to improve the design by using a different charger or protection IC.
Best regards,
Todor
