Power supply for electronic timepiece - has circuit to drop voltage level at low power consumption and prevent incorrect logic circuit operation when power source voltage drops

摘要

The power supply system for an electronic device such as a watch, calculator, includes a battery power source (1), a logic circuit (7), a voltage converter (4) which produces a lower voltage (V2) than the battery (V1), and a load circuit (3) to drop the output voltage of the battery power source (1). A voltage switch circuit (6) is provided for supplying selectively the output voltage (V1) from the battery (1) or the lower voltage from the voltage converter (4) to the logic circuit as drive voltage. In the system, the logic circuit (7) is usually operated by the lower voltage from the voltage converter (4). When the load circuit (3) operates, the logic circuit is operated by the output voltage from the battery power source (1).