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BQ25703A: Need to get the charger to output more than 100m Amps

John Mastroianni
Prodigy 90 points
Part Number: BQ25703A

Hi TI experts,

I am using the BQ25703A and having difficulty getting the charge current beyond ~ 100 mA. This is regardless of the register 03/02 setting. My setup is input voltage = 5 volts and Cell_BATPRES = 2S. At power up, all appears to be well according to the default register values. They are displayed below.

=> i2c md 0x6b 0x00

0000: 0e e2 00 00 d0 20 00 00 00 00 c0 01 00 18 00 41

When I do the following steps, the battery is charging and VSYS climbs from 7.5 to 7.97 (after an hour) volts but I am unable to get more than ~100mA to the battery. I wish to charge the battery at .4 amps. Here are the registers I am writing:

*/* set charge current = .4 amps

I2C mw 0x6B 0x02 0xC0

I2C mw 0x6B 0x03 0x01

 

*/* set the charge inhibit to start charging & disable watchdog timer

I2C mw 0x6B 0x00 0x02

I2C mw 0x6B 0x01 0x00

 

I am new to this device. Can you check the schematics and let me know if I should be programming other registers to perform a fast charge at .4 amps?

 

Thanks,

Jmast2

 

 

  • 0
    TI__Genius 10240 points

    Hi John,

    The register setting shows the charging current setting as 192mA and the battery voltage is 0V. Please provide full description of the operation such as "I2C mw 0x6B 0x02 0xC0" and reading back of registers. The charge status 21h[7] shows AC_STAT = 0b (Adaptor Not Present). Please also check the SW1 and SW2 waveforms. The schematic resolution is low and hard to read.

  • 0 in reply to ezhao
    Prodigy 90 points

    Hi Eric, I was able to get past the charging problem and now able to charge the battery at ~512 mAmps. Also, the charge voltage climbs to ~8.4 volts. This issue has been resolved and it can be closed.

    Thank you,

    John