In some applications, the output voltage needs to get to zero as soon as the device is disabled. For that, an internal discharge circuit is implemented inside the device to bleed off the remaining charge of the output capacitor as soon as the device is disabled. The purpose of the discharge function is to ensure a defined down-ramp of the output voltage when the device is being disabled but also to keep the output voltage close to 0 V when the device is off. The output discharge feature is only active once TPS629xx-Q1 has been enabled at least once since the supply voltage was applied. The internal discharge resistor is connected to the VOS pin. The discharge function is enabled as soon as the device is deactivated, in thermal shutdown or in undervoltage lockout. The user can turn this feature on or off using the smart configuration pin.

In the TPS621x0A-Q1, this feature is implemented using the PG pin. The TPS621x0A-Q1 pulls the PG pin low, when the device is shut down by EN, UVLO or thermal shutdown. Connecting PG to VOUT through a resistor can be used to discharge VOUT in those cases. The discharge rate can be adjusted by the pull up resistor, which is also used to pull up the PG pin in normal operation.