FAULT DETECTION APPARATUS FOR A TRANSFORMER ISOLATED TRANSISTOR DRIVE CIRCUIT FOR A POWER DEVICE

A protection circuit which electrically isolates logic level and high-side circuits and detects high side power device fault conditions at the isolated, logic level side of the circuit. When an overvoltage or overcurrent condition occurs at the power switching device, a protection circuit disables the conduction of current through the current carrying terminals of the switching device, preventing damage from occurring to the device. Activation of the protection circuit effects an increased current flow in the secondary and primary coils of the isolation transformer between the low side and high side elements. Voltage at the primary coil of the isolation transformer is monitored by low level circuitry to detect the rise in current, indicating a fault to the system controller upon detection.