Power supply control device

When a highly accurate clock is controlled via a GPS radio wave received through a GPS antenna (10), the highly accurate clock is always generated by locking a phase locked loop (PLL) circuit within a hold-over section of a clock control section in a power supply control unit. When the GPS radio wave cannot be received normally, the highly accurate clock depending on the GPS radio wave is set to a self-running condition not depending on a self-oscillation clock from an internal clock generating section (15) and a time management section (23) automatically corrects the present time data obtained when a standard radio wave is received from a radio wave antenna (13) based on the highly accurate clock. A primary voltage generating section (7) continuously generates the highly accurate clock even when an ignition switch (3) is turned OFF by avoiding voltage variation in battery voltages while the ignition switch (3) is turned ON. Accordingly, the power supply control device can sustain highly accurate time correction and a clock function under any environmental condition and can also control the execution of various functions based on accurate time management.