| 摘要 |
PURPOSE:To obtain an electronic watch with stable performance even under a heavy load, by selecting two sets of constant voltage circuits falling down a battery voltage to a different voltage at non-operation of heavy load and at operation of that. CONSTITUTION:When a heavy load such as generation of alarm tone is selected via a switch 105, an output of an encoder 106 is applied to an RSFF 122 of a power supply circuit 102 via a lamp illumination control circuit 114, an OR circuit 116 and a level shifter 119. etc. to set the RSFF 122. A transistor gate 120 is opened with the FF 122 and a transistor gate 121 is cloed and a power is applied to a control circuit 118 of a step-down/step-up control circuit 117. Thus, in place of a constant voltage circuit 124 which falls down the power supply battery selected at normal operation to a prescribed low voltage, a constant voltage circuit 125 which falls down the voltage to about a half the voltage of the circuit 124 is selected and power is supplied to the heavy load. On the other hand, the output voltage of the circuit 125 is boosted at the circuit 117 to be fed to a clock circuit, allowing to constitute an electronic watch with stable operation even with fluctuated power supply at the heavy load. |
