The LMG2650 implements separate overtemperature protection for both the low-side and high-side device circuits. The low-side overtemperature protection blocks the INL pin from turning on the low-side GaN power FET and blocks the INH pin from turning on the high-side GaN power FET if the low-side temperature is above the overtemperature protection temperature. The high-side overtemperature protection blocks the GDH pin from turning on the high-side GaN power FET if the high-side temperature is above the overtemperature protection temperature. Figure 7-3 shows the overtemperature blocking operation. The overtemperature protection hysteresis avoids erratic thermal cycling.

The low-side overtemperature protection is enabled when the AUX voltage is above the AUX Power-On Reset voltage. The low AUX Power-On Reset voltage helps the overtemperature protection remain operational when the AUX rail droops during a power converter cool-down phase. The high-side overtemperature protection is enabled when the BST-to-SW voltage is above the BST Power-On Reset voltage.

A low-side overtemperature fault is reported on the FLT pin when the low-side overtemperature protection is asserted. This is the only fault event reported on the FLT pin.