The enable function is a beneficial feature in applications where the controller is located on the secondary side of an isolation barrier, which is common with digital controllers. In these applications, it is easy to turn off the driver signal in a very short time when critical faults such as primary-side overcurrent occurs. The enable function response time is typically around 32ns.

The enable pin controls both the high-side and low-side driver-channel operation. The enable pin is based on a non-inverting configuration (active-high operation). Thus, when EN pin is driven high the driver is enabled and when EN pin is driven low the driver outputs are set low. The EN pin is internally pulled up to VDD using a 200kΩ pull-up resistor, therefore the outputs of the device are enabled in the default state. The EN pin may be connected to VDD, left floating, or Not Connected (N/C) for standard operation, when the enable feature is not needed. Care must be taken not to connect the EN pin to ground, which permanently disables the device. Like the input pins, the enable pin is also based on a TTL and CMOS compatible input-threshold logic that is independent of the supply voltage and is effectively controlled using logic signal from 3.3V and 5V microcontrollers. The UCC2773x-Q1 also features tight control of the enable-function-threshold voltage levels which eases system design considerations and ensures stable operation across temperature.