SLVSDV8 July 2017 TPS54424
The PGOOD pin is an open-drain output requiring an external pull-up resistor to output a high signal. Once the FB pin is between 91% and 106% of the internal voltage reference and SS/TRK is greater than 0.75 V, after a 272 cycle deglitch time the PGOOD pin is de-asserted and the pin floats. A pull-up resistor between the values of 10 kΩ and 100 kΩ to a voltage source that is 6.5 V or less is recommended. PGOOD is in a defined state once the VIN input voltage is greater than 1 V but with reduced current sinking capability.
When the FB is lower than 89% or greater than 108% of the nominal internal reference voltage, after a 16 cycle deglitch time the PGOOD pin is pulled low. PGOOD is immediately pulled low if VIN falls below its UVLO, EN pin is pulled low or the TPS54424 enters thermal shutdown.