Hi,
I'm bringing up a new BMS design using a bq20Z24-R1. I am having problems with the FET drive. I can make the DSC FET turn on and off by writing SMBus Cmd 0x46 with the data 0x0002 to turn on and 0x0000 to turn off. However, I have noted that the gate drive voltage is only swinging to the value of VBAT (~10Volts in this case). My understanding is that the internal charge pump driver should drive the DSC pin to a value of 8 to 16V above FET source pin voltage. As per the datasheet ref schematic, I have a 3meg resistor from G to S and a series 5.1K from G to DSC on the chip. Both the 3.3V ansd 2.5V LDO regulators measure fine. I am not using any of the other Fet drivers as this is a primary battery design. Can you help me determine the solution to this problem?