FAULT DETECTION CIRCUIT FOR OSCILLATION CIRCUIT AND PROTECTION CIRCUIT FOR INVERTER USING THE FAULT DETECTION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To detect abnormality of a clock signal with a simple circuit configuration.;SOLUTION: A leading detection circuit 2 detects a leading of a clock signal (a) and an integrator 3 with a reset switch is reset by a leading detection signal (c) and starts integration of the clock signal between the leading detection signals (c). The integrator 3 integrates the clock signal for one period when the clock signal is normal. When the clock signal is faulty, since the leading detection circuit 2 cannot output a next leading detection signal, an output (d) of the integrator 3 rises near a power supply voltage. A comparator 4 compares an output (d) of the integrator 3 with a setting voltage set higher than the output (d) of the integrator in a normal state of the clock signal and provides an output of a fault detection signal (e) when the output of the integrator 3 is higher than the setting voltage. Since the fault detection circuit comprises the leading detection circuit 2, the integrator 3 and the comparator 4, the fault detection circuit can surely detect a fault of the clock signal with a simple circuit configuration.;COPYRIGHT: (C)2002,JPO