The TPS3431-Q1 features an active-low open-drain watchdog output that asserts when a pulse on WDI fails to arrive within the watchdog timeout. When EN is logic high, the WDO signal maintains normal operation. When the EN pin is logic low, the WDO pin goes to a high-impedance state and pulls logic high due to the external pull-up resistor. Because WDO and ENOUT are both open-drain outputs, these outputs can be tied together to create an OR logic function so that if either output pulls down to logic low, the other will also pull down logic low.