Mosfet Driver for BQ76930/76940

Hi Alexey,
The bq76200 provides 3 functions needed in the high side battery switch application:
1. A charge pump to provide a supply for a gate voltage for the N-channel MOSFETs above the battery voltage.
2. A level shifter to take the control signals from ground based levels to the level of the FETs.
3. Drivers for the FET gates with appropriate signal swings. With the common drain FET configuration the charge FET control swings from battery to battery+gate voltage while the discharge FET control swings from 0V to battery+gate voltage.
The bq76200 has fixed internal resistances for the drivers. The size of the charge pump capacitor can be scaled to provide for more capacity for more FET gates, but the switching will slow as more FETs are paralleled as shown in the captures in the FET configuration apnotes. At some point the switching may become too slow for your system.
Another gate driver could work, it needs to provide the same features for the system as described above. The LM5111 is certainly a capable driver but does not provide the level shift, the supply or the voltage swing for a battery switch FET configuration.

Hi Alexey,
There is no way to synchronize the outputs of 2 bq76200 devices. While the propagation delay through the driver is likely a small portion of the switching delay that you see between the input command and the current change in the FETs, differences in the FETs or the resistances internal or external to the bq76200 may make one path faster and cause the load to shift to one group of FETs. While parallel FETs with the same driver will share current, with different driver the stronger driver would win and the FETs on the slower/weaker driver would take the current during turn off.
Using 1 device for charge FETs and one for discharge FETs would reduce the load on the charge pump but would not help the internal driver resistance from the charge pump to the output pin or the output pin to the "off" reference (BAT for CHG or PACK for DSG).
The real concern is not the number of FETs but the switching speed. If you have FETs with a low Ciss (or gate charge), the 20 FETs may switch faster than 10 FETs with large Ciss. Consider circuits you could add to buffer the output. If they don't load the charge pump It may be practical to use the bq76200 for the level shifter and charge pump voltage and external buffers for the drivers, but realistically there will come a point where it may be more efficient to create your own circuit.

Thank You, for the good answers.