Abstract: The invention provides a rechargeable electronic timepiece that restarts the operation of a clock circuit by inputting a power source, thereby securely confirming the clock operation. The electronic timepiece includes a first power source (2), a clock circuit (8) connected to the first power source, a power source input detecting circuit (86) for detecting an input of a second power source (3), a switch circuit (7, 9) for connecting the first power source and the second power source, and a control circuit (87) for controlling the switch circuit to connect the first power source and the second power source so that the first power source is charged by the second power source thereby operating the clock circuit when the power source input detecting circuit detects an input of the second power source.

Abstract: A constant voltage generating circuit according to the present invention includes a reference voltage generation source 1, a differential amplifier 2 that receives an output voltage (REF1) of the reference voltage generation source 1 at one terminal and receives a potential (VREF2), generated by adding a predetermined potential difference to a regulator voltage (VREG), at another terminal, and switching means 6 that controls the current amount of an output terminal 10 of the reference voltage generation source 1 so that the current amount increases for a fixed period of time immediately after the power is turned on. The switching means 6, which is turned on/off based on VREF2, stabilizes the output voltage (REF1) of the reference voltage generation source 1 quickly after the power is turned on and then stabilizes the regulator voltage (VREG).

Abstract: A constant voltage generating circuit according to the present invention includes a reference voltage generation source 1, a differential amplifier 2 that receives an output voltage (REF1) of the reference voltage generation source 1 at one terminal and receives a potential (VREF2), generated by adding a predetermined potential difference to a regulator voltage (VREG), at another terminal, and switching means 6 that controls the current amount of an output terminal 10 of the reference voltage generation source 1 so that the current amount increases for a fixed period of time immediately after the power is turned on. The switching means 6, which is turned on/off based on VREF2, stabilizes the output voltage (REF1) of the reference voltage generation source 1 quickly after the power is turned on and then stabilizes the regulator voltage (VREG).

Abstract: An oscillation-stop detection circuit includes a switching unit that repeats turning on and off based on a cycle of an oscillation signal from an outside; a capacitor that is charged when the switching unit is turned on, and discharged when the switching unit is turned off; a first MOS transistor that flows a discharge current of the capacitor when the capacitor is discharged; a discharge cutoff unit that cuts off a discharge path for the discharge current to flow, for a predetermined time right after a power is turned on; and a detecting unit that detects a status of the oscillation signal based on a voltage of the capacitor.

Abstract: The invention provides a rechargeable electronic timepiece that restarts the operation of a clock circuit by inputting a power source, thereby securely confirming the clock operation. The electronic timepiece includes a first power source (2), a clock circuit (8) connected to the first power source, a power source input detecting circuit (86) for detecting an input of a second power source (3), a switch circuit (7, 9) for connecting the first power source and the second power source, and a control circuit (87) for controlling the switch circuit to connect the first power source and the second power source so that the first power source is charged by the second power source thereby operating the clock circuit when the power source input detecting circuit detects an input of the second power source.

Abstract: An oscillation-stop detection circuit includes a switching unit that repeats turning on and off based on a cycle of an oscillation signal from an outside; a capacitor that is charged when the switching unit is turned on, and discharged when the switching unit is turned off; a first MOS transistor that flows a discharge current of the capacitor when the capacitor is discharged; a discharge cutoff unit that cuts off a discharge path for the discharge current to flow, for a predetermined time right after a power is turned on; and a detecting unit that detects a status of the oscillation signal based on a voltage of the capacitor.