Abstract: A power supply circuit is disclosed that includes a coil with first and second ends having supply voltage applied to the first end, a first switching element connected between the second end of the coil and ground, a second switching or diode element supplying current to a load after rectifying the current in accordance with voltage generated at the connection of the coil and the first switching element, a driver circuit switching at least the first switching element, a third switching element connected in series to the load, and a power supply stop circuit switching off the first element so as to stop supplying power to the load and switching off the third element so as to stop supplying the current to the load in accordance with an external signal.

Abstract: A power supply circuit is disclosed that includes a coil with first and second ends having supply voltage applied to the first end, a first switching element connected between the second end of the coil and ground, a second switching or diode element supplying current to a load after rectifying the current in accordance with voltage generated at the connection of the coil and the first switching element, a driver circuit switching at least the first switching element, a third switching element connected in series to the load, and a power supply stop circuit switching off the first element so as to stop supplying power to the load and switching off the third element so as to stop supplying the current to the load in accordance with an external signal.

Abstract: An error amplifier stage (32) is supplied with an input signal from an input terminal (Vin) and a feedback signal produced by an output current/voltage converter stage (34) and amplifies the input signal with reference to the feedback signal to produce an amplified current signal which is delivered to a load driver stage (33). The error amplifier stage comprises an operational amplifier (6) of a voltage-controlled current-output type which is a transconductance amplifier having a transconductance gm. The transconductance amplifier includes a constant-current source and serves as a differential amplifying circuit based on the transconductance gm. A phase adjusting circuit for the transconductance amplifier is formed by a combination of a resistor (R10) and a capacitor (C10) connected in series between an output terminal of the transconductance amplifier and a ground potential.