Output discharge function is used to make sure that output voltage discharge quickly when the device is disabled. This is necessary when the power system requires exact power sequencing for different circuits and components. Without output discharging function, some power rails are left floating when the system is disabled, and this probably cause some issues when the system is enabled again.

TPS61033 can implement output discharge function by PG function that requires a pull-up resistor connected between PG pin and Vout pin, this pull-up resistor is also called dummy resistor (R_Dummy). As mentioned above, PG of TPS61033 is an open drain NMOS architecture with up to 50 mA current capability, the PG pin becomes logic high when the output voltage reaches the target value, so the dummy load resistor doesn't lead any power loss during normal operation. When the EN pin gets low, the TPS61033 is disabled and meanwhile the PG pin gets low with a typical 33 μs glitch time (tglitch). With PG pin keep low, the dummy resistor works as a dummy load to discharge output voltage. Changing R_Dummy can adjust the output discharge time and discharge current.