Tool/software:
Hi,
I am using a combination of the TPS25751D and BQ25731 to implement a dual role USB-C PD system. The circuit I am using are a copy of the typical application supplied in the ICs datasheet. As for the bin file for the TPS25751D, the application customization tool does still not permit to use the BQ25731 so I have been supplied with a custom bin file to use in this thread (https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1396813/tps25751-bin-file-for-bq25731/5348643#5348643).
My system will charge a 4S Li-ion battery, at 5A during CC and entering CV at 16.752V. I am currently powering the USB-C port using a 60W USB-C PD charger, thus CC current starts decreasing while the battery voltage increases since the input power to the battery is limited to 60W (this is normal). The issue I am experiencing is that at low battery voltages (12V - 13V), the BQ25731 starts charging at a CC current of roughly 4.5A (good) but after a couple of minutes, the CC current drops to 0.3A and stays there. I tried to find reasons why this is happening but could see anything. Are there any SW or HW settings which might be causing this to happen?
Thanks
UPDATE
While in this state, I managed to connect an EV2300 to the BQ25731 and get the charger settings. I noted that the charging current was set to 256mA. I manually changed this value to 4.5A and the CC charging went up to 4.1A, (battery voltage was 13.681V and source is limited to 60W, thus its good). This means that somehow, during CC charging, the charging current register value is changing, either by its own, or the TPS25751D is for some reason changing it.
Are there any reasons why this could be happening? Since I am limited to 60W and thus the charging is basically happening at constant power (current decreasing while voltage is increasing to maintain a max power of 60W), can it be that the TPS25751D is constantly updating the charging current register and at some point it send an incorrect value?
