BQ76952: 0V charging

Hi Zhang,

The BQ76952 does not have a zero vollt charge function. It is powered from the battery side by the BAT pin, if this voltage is too low it will not start and can not run the charge pump to turn on the CHG driver. It does not have a source follower mode.  The part does have a shutdown level which is programmable, see the technical reference manual section 13.4.1.1 Power:Shutdown:Shutdown Cell Voltage and 13.4.1.2 Power:Shutdown:Shutdown Stack Voltage 

The part can be awakened if the voltage is above the VPORA level in the data sheet.  Power for the regulator is normally drawn from the common drain connection between the FETs so the regulator current can be provided by the charger voltage if present, avoiding a large draw on the battery.  If the part configuration allows charge the battery could be charged. See the description and note in section 7.5 SHUTDOWN Mode.  So while the part does not have a 0-V charge mode, if the voltage on the stack is sufficient to wake the part, it could charge cells which have a very low voltage.