| 摘要 |
PURPOSE: To provide an on-vehicle clock device which can reduce the power consumption and whose clocking accuracy can be enhanced and to provide a clocking method for on-vehicle clocks. CONSTITUTION: An on-vehicle clock device is provided with a quartz oscillator XT1 on the CPU 20 side and with a quartz oscillator XT2 for a PTC circuit 25. The clock device is provided with a battery-voltage monitoring circuit 16 which monitors the voltage of a battery 12. When the battery 12 is in an OFF state by its monitoring signal, time data is created by the quartz oscillator XT2 for the RTC circuit 25. When the battery 12 is in an ON state, the time data for the RTC circuit 25 is written into a time-data area in a RAM 24 for the CPU 20, and time data is created. |
