Depressing and then releasing pushbutton SW4 causes net PS_POR_B to strobe Low. This reset is used to hold the PS in reset until all PS power supplies are at the required voltage levels. It must be held Low through PS power-up. PS_POR_B should be generated by the power supply power-good signal. When the voltage at IN1 is below its threshold or EN1 (P.B. switch SW4 is pressed) goes Low, OUT1 (PS_POR_B) goes Low.