The maximum voltage rating of the switching node and BOOT pins is 30 V. The limit of 30 V on the BOOT1 and BOOT2 pin voltage should be strictly enforced. If the voltage spike of BOOT1 or BOOT2 is above 30 V during operation, the internal boot diode might be damaged and result in permanent failure. To reduce the voltage spike on the switching node, the R-C snubber can be added. Furthermore, the BOOT resistor can be added to slow down the turn-on of high-side switch. If the voltage spike remains above 30 V with an R-C snubber and a boot resistor, add a gate resistor as shown in Figure 8-5 to slow down the turn-on time of the high-side switch and to further reduce voltage spikes. To eliminate the impact of the gate resistor to the turn-off time of the high-side switch, place a Schottky diode in parallel with the gate resistor.

If the approaches described in this section do not reduce the BOOTx voltage to within 30 V, add an external BOOT diode between the BP6 pin and the BOOTx pin. The forward voltage of the external BOOT diode must be less than that of internal BOOT diode and the voltage rating should be higher than the BOOT voltage spike.

Figure 8-5 Adding a BOOT Resistor and Gate Resistor