摘要 |
A safety circuit 16 for monitoring the waveform of a start signal outputted from a microcomputer 40a is provided in a power supply circuit. If a start signal inputted to the safety circuit 16 is not a pulse wave, a power supply cutoff section 16c cuts off the output of the start signal to a DC/AC circuit 13, thereby cutting off the supply of power by the DC/AC circuit 13 from a primary side to a secondary side. Thereby, it is possible to prevent the supply of power by the power supply circuit without providing an additional microcomputer or IC for monitoring a failure and a temporary malfunction of a control microcomputer and to safely prevent the supply of power at the time of a latch-up caused by noise or a breakage.
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