Rohm Co., Ltd.

Zhencheng Jin

Hiroki Inoue

Kotaro Iwata

Makoto Yasusaka

A power regulator has an input terminal to receive an input voltage, an output terminal to output an output voltage, a transistor connected to the input and terminals, a feedback terminal to receive a feedback voltage, and a control circuit to control the transistor based on the feedback voltage at the feedback terminal and a reference voltage so as to keep the output voltage constant. Various implementations include an open detection circuit to detect an open state of the feedback terminal and, on detecting the open state, to vary the reference voltage and thereby keep the transistor in an OFF state, or a voltage holding circuit configured to hold the output voltage constant at a second voltage lower than the first voltage when the feedback terminal is in an open state.

Power regulator to control output voltage using feedback

A linear power supply () includes a P-channel (or PNP) first output transistor () connected between an input terminal of an input voltage (Vin) and an output terminal of an output voltage (Vout), an N-channel (or NPN) second output transistor () connected in parallel to the first output transistor (), and a control circuit () that switches between a first mode and a second mode according to the input voltage (Vin), in which the first mode uses the first output transistor () while the second mode uses the second output transistor () as an output transistor that generates the output voltage (Vout) from the input voltage (Vin).

Linear power supply and electronic apparatus using same

A linear power supply circuit includes a first output transistor of a P-channel type or pnp type which is connected between an input terminal to which an input voltage is input and an output terminal from which an output voltage is output; a first differential amplifier configured to amplify a difference between the output voltage or a feedback voltage according to the output voltage and a predetermined first reference voltage and output a first amplification voltage; a second differential amplifier configured to amplify a difference between the input voltage or a first monitor voltage according to the input voltage and the output voltage or a second monitor voltage according to the output voltage and output a second amplification voltage; and a first driver configured to generate a control voltage of the first output transistor according to the first amplification voltage and the second amplification voltage.

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Kyoto, Japan

Zhencheng Jin