This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ25792: BQ25792 SYS query

Part Number: BQ25792
Other Parts Discussed in Thread: BQ25798


The customer design the schematic and then supply voltage to VBUS find the SYS output voltage unstable.

Attached the schematic and waveform for your reference.


If use battery(Vbat>3.5V) or VBUS + Vbat (Vbat>3.5V,REG00 default setting) ,SYS output voltage is stable.

Why only supply VBUS the output voltage unstable?

Waiting for your reply.



  • Hi Star,

    The BQ25792 was designed expecting that when the battery is removed either charge would be disabled by CE bit/pin or the removed thermistor would cause a TS fault and disable charge.  With VBUS applied and no battery, the charge current turns on fast, causing a BATOVP fault, which then cause a SYSOVP fault.  The faults then cause the converter to stop.  Adding a large capacitance at BAT (470uF) usually prevents the OVP event. 

    The soon-to-release BQ25798 with same pin out changes the timing of the faults so that the converter does not shut down.