SLUSE14B December 2020 – December 2021 BQ76942
The BQ76942 device includes precharge functionality, which can be used to reduce the charging current for an undervoltage battery by charging using a high-side PCHG PFET (driven from the PCHG pin) with a series resistor until the battery reaches a programmable voltage level. When the minimum cell voltage is less than a programmable threshold, the PCHG FET is used for charging.
The device also supports predischarge functionality, which can be used to reduce inrush current when the load is initially powered, by first enabling a high-side PDSG PFET (driven from the PDSG pin) with a series resistor, which allows the load to slowly charge. If PREDISCHARGE mode is enabled, whenever the DSG FET is turned on to power the load, the device will first enable the PDSG FET, then transition to turn on the DSG FET and turn off the PDSG FET.
The PCHG and PDSG drivers are limited in the current they can sink while enabled. As such, it is recommended to use 1 MΩ or larger resistance across the FET gate-source.