| 摘要 |
PURPOSE:To enable continuance of normal running operation, by providing a high-reliable backup circuit which, even when a microcomputer is inoperative, maintains minimum ignition function and enables the performance of normal running operation. CONSTITUTION:In a backup signal generating circuit 6, a reference angle signal 3A and an angle signal 3B are inputted and a backup signal 6A with a specified pulse width is also outputted. A number coincidence detecting circuit 7 monitors operation of a microcomputer 4, and outputs a monitor signal 7A. A selection switching circuit 8 is atuated according to a monitor signal 7A, during normal operation, an ignition signal 4A from the microcomputer 4 is selected, and during abnormal operation, the backup signal 6A from the backup signal generating circuit 6 is selected to output an output ignition signal 8A to an igniting device 9. The signal 8A is energized to an ignition coil 10, and a generated high voltage is guided to an ignition plug 12 through a distributor 11 to ignite, in order, cylinders.
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