The active pulldown function is used to pull the IGBT or MOSFET gate to the low state when no power is connected to the VCC2 supply. This feature prevents false IGBT and MOSFET turnon on the OUT, OUTL, and CLAMP pins by clamping the output to approximately 2 V.
When the output stages of the driver are in an unbiased or UVLO condition, the driver outputs are held low by an active clamp circuit that limits the voltage rise on the driver outputs. In this condition, the upper PMOS is resistively held off by a pullup resistor while the lower NMOS gate is tied to the driver output through a 500-kΩ resistor. In this configuration, the output is effectively clamped to the threshold voltage of the lower NMOS device, which is approximately 1.5 V when no bias power is available.