BQ27621: 0% SOC Crash

JoFu10

Hi,

We have a setup going where our main firmware would interrogate the fuel gauge continuously over the I2C for three registers: the SOC data; the flag register; the control status register.

We were able to observe that every time a SOC value of 0% was read from the fuel gauge, the ITPOR bit in the flag register would be set, and the INITCOMP bit in the control status register would be cleared temporarily.

Is it correct to say that the device has crashed and the SOC value of 0% is because the gauge is still initializing?

Thanks,

Josh

over 9 years ago

0 Dominik Hartl11 over 9 years ago

TI__Guru 62076 points

Yes, if ITPOR is set then the gauge was reset. How many times per second do you poll the gauge?

0 JoFu10 over 9 years ago in reply to Dominik Hartl11

TI__Intellectual 2385 points

Hi Dominik,

We are polling the gauge once every second, and each poll took 0.9ms.

It may be not pertinent, but we were testing with the bypass cap for the 1.8V LDO removed, and we got errors every 30ish tries, but with the cap on, we got errors after about an hour.

How long would it take for the gauge to come out of reset and finish initialization and have the INITCOMP bit set?

Thanks,
Josh

0 Dominik Hartl11 over 9 years ago in reply to JoFu10

TI__Guru 62076 points

The dependence on the LDO capacitor points to a POR due to a problem with the power supply. What's the terminate voltage in your system? It takes several seconds to set the INITCOMP bit, depending on how stable the battery voltage is.

Power management

Power management forum

BQ27621: 0% SOC Crash