The regulator has an internal metal-oxide-semiconductor field-effect transistor (MOSFET) that connects a pulldown resistor between the output and ground pins when the device is disabled to actively discharge the output voltage. The voltage on IN must be high enough to turn on the pulldown MOSFET; when V_IN is too low to provide sufficient V_GS on the pulldown MOSFET, the pulldown circuit is not active. The active discharge circuit is activated by the enable pin, or by the voltage on IN falling below the undervoltage lockout (UVLO) threshold.

Do not rely on the active discharge circuit for discharging a large amount of output capacitance after the input supply has collapsed because reverse current can possibly flow from the output to the input. This reverse current flow can cause damage to the device. Limit reverse current to no more than 5% of the device rated current for only a short period of time.