An electronic device in which a braking torque can be increased while reduction in power generation is suppressed, and in which a rotor is prevented from stopping or rotating at an excessive speed. Such an electronic device includes a generator which is driven by an mechanical energy source and a rotation controller which controls the rotational period of the generator. The rotation controller includes two switches which connect both terminals of the generator in the form of a closed loop, a chopping signal generator which generates a chopping signal that is applied to the switches, and a brake control circuit which performs chopper control of the generator by selectively switching between three brake control modes including a high-power brake control mode in which the effective braking force generated by applying the chopping signal is relatively large a low-power brake control mode in which the effective braking force is relatively small, and a mid-power brake control mode in which the effective braking force is between that of the high- and low-power brake control modes.
An electronically controlled timepiece includes an analog circuit (160) driven by a power source (22), a logic circuit (170) driven by a constant voltage regulator circuit (161) forming part of the analog circuit, an oscillator circuit (51) driven by the constant voltage regulator, a power source switch (162) for cutting off the supply of power to the analog circuit other than the constant voltage regulator circuit from the power source during a time correction operation, and a clock cutoff gate (171) for cutting off a clock input from the oscillator circuit to the logic circuit. During the time correction operation, power consumption is reduced because only the oscillator circuit and the constant voltage regulator circuit are operative. The oscillator circuit is not suspended, and an error in time display is eliminated.
