| 摘要 |
PURPOSE:To achieve cost reduction by providing the output means of a DC/DC converter with a capacitor, and detecting an upward change in voltage in a predetermined time. CONSTITUTION:When an ignition switch 2 is turned on, operation of an oscillating circuit 5 is initiated to start charging a backup capacitor 11, and an AND gate 15 is opened so that a counter 16 starts counting pulses output from the oscillating circuit 5. A predetermined period of time after counting of the pulses has been started, a signal for reading the voltage V1 of the capacitor 11 is supplied to an arithmetic processing circuit 13' from the counter 16, and a signal for reading voltage V3 is supplied after a predetermined period of time has further elapsed. These two voltage values V1, V3 are read by the arithmetic processing circuit 13' and the normality or abnormality of the capacitor 11 is determined from the voltage difference. Since the capacitor 11 is incorporated into the DC/DC converter 7, the overall constitution of the capacitor is simplified and the cost is reduced. |
