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BQ25122: BQ25122 Battery Monitor with Vin present

Lasse Korff
Prodigy 30 points
Part Number: BQ25122
Other Parts Discussed in Thread: BQ25120

Hi there!

We are trying to monitor VBAT on the go while charging, but I seem to have difficulties triggering a new measurement by writing a 0x0b10000000 to BQ25120_BATT_VOLT_MONITOR_REG.

It seems the relative value is updated when I remove VIN supply though. How do I measure battery voltage on the fly?

We would like to use this measurement in order to minimize the drop across the TI chip. The idea is to on the fly adjust VBATREG and VINDPM threshold and then also read the VINDPM_STATUS bit to see if we are above or below the VINDPM voltage. What is your take on this? Would this be possible?

Best regards.

  • +1
    TI__Genius 12475 points

    Hi Lasse, 

    Can you detail how you were performing this measurement?

    You will need to raise the /CD pin, write the VBMON_READ bit, wait for 2ms and then read back the batterymonitor voltage as a percentage of VBATREG. VBMON is 0x0A and not 0x0B. 

    What is the input supply to the BQ device- is that from a current limited source or a voltage converter? You can certainly adjust VBATREG on the fly with CD pin high to prevent overcharging the battery. The method itself is possible. 

    Regards,

    Gautham