| 摘要 |
PURPOSE:To surely execute the write processing of write data after power failure is recovered in a short time even when the power failure is caused while write processing to an EEPROM is being executed. CONSTITUTION:A DC output is received from a commercial power source 5 through a transformer 4, full wave rectifier circuit 6 and capacitor 7 for smoothing, and a prescribed voltage is supplied to a control circuit 1 and an EEPROM 2 by a constant voltage circuit 9. A capacitor 11 for backup is installed on the input side of the constant voltage circuit 9. A power failure detection circuit 12 detects the generation of power failure from the secondary side output of the transformer 4 and applies its detecting signal to the control circuit 1. When the write data are generated, the control circuit 1 executes the write processing to the EEPROM 2 while dividing them into plural minimum write unit data and when the power failure occurs, the control circuit interrupts the write processing after the minimum write unit data are completely written. When the power failure is recovered in a power feeding state, the write processing is continuously executed. |
