Over-Voltage Protection

The dead-time control input (pin 4) also provides a convenient input for over-voltage protection, which may be sensed as an output voltage condition, or input voltage protection as shown in Figure 6-18.

Figure 6-18. Over-Voltage Protection Circuit

A TL431 is used as the sensing element. When the monitored supply rail voltage increases to the point that 2.5 V is developed across R2, the TL431 conducts, 01 becomes forward biased, and the dead-time control is pulled up to the reference voltage which disables the output transistors.