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BQ25792: BQ25792: SYS output and BAT output were not regulated.

Part Number: BQ25792


                I'm using BQ25792 to charge my 14.4V battery in 4S mode (PROG connected  to 18K). when i am giving the input voltage 20V at VAC1 / VAC2 , the system voltage was not regulated to 12V. it was approximately equals to VBUS. Battery voltage was also equal to VBUS (19.6v).

There is no TS ERROR. CE pin was connected to ground. battery not connected. I2C operation was successful.  I am able to read and write the registers. but the voltage was not regulated to SYSMIN (12V) why?.

Please Reply me.

Thank you.

  • Hi Nakka,

    The EVM is configured with 10kohm resistor to simulate a thermistor.  Therefore, with no battery connected, there is no TS fault.  The battery voltage overshoots, causing SYS to overshoot, tripping both BATOVP and SYSOVP.  This results in the converter shutting down.  If your battery will always have a thermistor, I recommend removing JP18 to remove the 10kohm resistor that simulates the thermistor when the battery is not attached.