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BQ24257 OVP register issue

Dan Wieland
Intellectual 2625 points
Other Parts Discussed in Thread: BQ24257

I am having a hard time with the BQ24257.  I am currently running it off of a 7V voltage supply, which is over the default over voltage limit of the IC.  I override the default by writing register 7 (address 0x06) to 0xF0 which according to the datasheet should set the OVP voltage to 10.5 volts.  Problem is I am still seeing the input OVP fault (bits 5 and 4 of register 1 set to “11” and bits 3 to 0 set to “0001”).  I have checked with the scope and verified that the input voltage is clean (and is indeed at 7V).  I also tried disconnecting the battery from the charger to see if the fault would change (to unconnected battery), but I am still getting the same OVP fault.

 Any ideas?

  • 0
    TI__Expert 7730 points

    Hello Dan,

    I verified on bench using our EVM and I2C GUI that once the OVP is programmed to 10.5V through I2C, the IC will start charging with a valid battery. There are a few things that I will recommend the customer to check:

    - After writing to register 7 to program the OVP, can he read back what he wrote correctly?

    - What is the battery voltage when he saw BAT_OVP fault? If the battery is below 4.3V and the BAT_OVP fault happens, I would double check if the 12C communication is working correctly.

    The bq24257 EVM is available on ti.com, the other option is to order an EVM for the customer to check for the major functions using our software and GUI. At the same time, can you also send the schematic to me so that I can review if anything else could go wrong?

    Thanks,

    Wenjia