The RST/EN pin has two functions. It can be used to enable and shut down the outputs of the driver and reset the fault signaled on the FLT pin. The RST/EN pin needs to be pulled up to enable the device; when the pin is pulled down, the device is in disabled status. With a 50-kΩ pulldown resistor existing, the driver is disabled by default.

When the driver is latched after an overcurrent or short circuit fault is detected, the FLT pin and output are latched low and need to be reset by the RST/EN pin. The RST/EN pin is active low. The microcontroller needs to send a signal to the RST/EN pin after the fault mute time t_FLTMUTE to reset the driver. This pin can also be used to automatically reset the driver. The continuous input signals IN+ or IN- can be applied to the RST/EN pin, so the microcontroller does not need to generate another control signal to reset the driver. If the noninverting input IN+ is used, then IN+ can be tied to the RST/EN pin. If inverting input IN- is used, then a NOT logic is needed between the inverting PWM signal from the microcontroller and the RST/EN pin. In this case, the driver can be reset in every switching cycle without an extra control signal from the microcontroller to the RST/EN pin.

Figure 9-4 Automatic Reset Control