Gate drivers with an enable or shutdown pin offer the flexibility to turn off both outputs of a half-bridge driver regardless of the input signal with a single pin. This feature can be valuable in systems where rapid response to a fault is a priority. Using the enable or shutdown pin, the gate driver outputs can be quickly switched low and the PWM input disabled in response to a detected fault and help bring the system to a steady state. This feature is also important to half-bridge drivers with a single PWM input as there is no way to create an off state (HO and LO both off) without an enable or shutdown pin or powering down the device. The shutdown or enable pin can have inverting or normal logic depending on the device.

In a multiphase power converter, this feature also allows for unused phases to be switched on and off in response to load conditions. Efficiency is improved by shedding additional phases when the switching losses are higher at light loads and adding phases to reduce the conduction losses in each phase with heavy loads. The enable or shutdown pin can also be used to decrease standby current consumption by shutting down the gate driver when switching is not needed.

Figure 2-3 shows LM2104 as an example of a gate driver with a single PWM input and an inverting shutdown pin.