JAJSOF1C December 2022 – June 2024 TPS7A21-Q1
PRODMIX
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. Make sure the voltage on IN is high enough to turn on the pulldown MOSFET. When VIN is too low to provide sufficient VGS 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 collapses. Reverse current potentially flows from the output to the input. This reverse current flow potentially causes damage to the device. Limit any such transient reverse current to no more than 5% of the device rated current.