Hello everyone,
This is my problem. I am using BQ25886 for building a USB powered charging circuit on my device. I have a 2 cell Li-ion battery with 7.4 V nominal voltage. The measured charging current is 750 mA instead of the set value of 1.2 A. I am using several different wall adapters with maximum output current of 2.4A.
I am attaching the schematics of my charging block.
The input current is set to the maximum value of 3A via shorting ILIM pin to GND (R15 = 0 Ohm).
The charging voltage is set to 8.2 V via shorting VSET pin to GND (R16 = 0 Ohm).
The charging current is set to 1.2A (R17 =4k7)
Since I am not using a thermistor, I connected the TS pin to a voltage divider, that sets the TS voltage to 50% of the REGN voltage. According to page 9 from the datasheet, this voltage should be between 45 and 68 % of VREGN in order to have a full charging current. I tried also the divider configuration from page 21 (R24 =4.7k, R25 =27k in parallel with 10k, resulting in TS voltage =60% of VREGN) and the charging current was still 750 mA.
Additional information is that I have the data lines of the USB connected to an FTDI USB to UART translator chip. However, disconnecting the FTDI didn’t fix the charging current.
I have tried also to bypass transistor T3 from my false polarity protection circuit but it had no effect neither. Instead of the fuse R14 I have a 0 Ohm resistor.
I hope my description of the schematics and the issue is detailed and clear enough. I am looking forward for any ideas and suggestions. Thank you in advance.
Best Regards
Angelo
