摘要 |
An internal power circuit lowers a battery voltage supplied always from an external side to generate a standby power voltage. A timer continues to measure an elapse of time in a standby state, after a main relay is turned off and supply of a power voltage is interrupted. A measured time data of the timer is saved to a save register during a time measurement operation of the timer. When a stop condition for stopping the time measurement operation of the timer is satisfied, a control circuit stops the operation of the internal power circuit. When the main relay is turned on, the internal power circuit is activated to start its operation again by the control circuit so that the measured time data saved to the save register is restored to the timer.
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