Disclosed here is a linear regulator circuit including an input line, an output line, a P-channel output transistor connected between the input line and the output line, a feedback circuit that performs feedback control on a gate voltage of the output transistor such that an output voltage of the output line approaches a target level, and a protective circuit that clamps the gate voltage of the output transistor such that the gate voltage does not fall below a voltage level lower than the output voltage by a predetermined voltage.

Disclosed here is a linear regulator circuit including an input line, an output line, a P-channel output transistor connected between the input line and the output line, a feedback circuit that performs feedback control on a gate voltage of the output transistor such that an output voltage of the output line approaches a target level, and a protective circuit that clamps the gate voltage of the output transistor such that the gate voltage does not fall below a voltage level lower than the output voltage by a predetermined voltage.

A low-dropout regulator includes a comparator for comparing a feedback voltage with a reference voltage to output a comparison signal, which corresponds to a comparison result, to a control node; an internal voltage generator coupled to the control node, and for generating the feedback voltage and an internal voltage based on the comparison signal; and a controller coupled to the control node, and for monitoring the internal voltage based on the comparison signal, and controlling a voltage level of the comparison signal according to a monitoring result.

A low dropout voltage regulator includes a differential amplifier configured to output an amplified voltage by comparing a feedback voltage with a reference voltage, a pass transistor configured to receive a power input voltage into a source terminal, the amplified voltage into a gate terminal, and output an output voltage into a drain terminal, distribution resistors connected between the drain terminal and the ground terminal, configured to generate the feedback voltage, and an inrush preventer, connected in parallel between the differential amplifier and the pass transistor, and configured to output a regulated amplified voltage into the gate terminal according to a control signal, wherein the inrush preventer comprises a determiner configured to output an enable signal that is turned on during an initial driving period, and a limiter configured to output the regulated amplified voltage according to the enable signal.

A low dropout voltage regulator includes a differential amplifier configured to output an amplified voltage by comparing a feedback voltage with a reference voltage, a pass transistor configured to receive a power input voltage into a source terminal, the amplified voltage into a gate terminal, and output an output voltage into a drain terminal, distribution resistors connected between the drain terminal and the ground terminal, configured to generate the feedback voltage, and an inrush preventer, connected in parallel between the differential amplifier and the pass transistor, and configured to output a regulated amplified voltage into the gate terminal according to a control signal, wherein the inrush preventer comprises a determiner configured to output an enable signal that is turned on during an initial driving period, and a limiter configured to output the regulated amplified voltage according to the enable signal.

A circuit comprises an optical coupling including an illuminator optically coupled to an optical sensor to output a voltage from the optical sensor based on intensity of illumination from the illuminator. The circuit includes a voltage input node with a resistance connected in series between the voltage input and a Zener diode. A method includes powering an illuminator with current from a first voltage input node. The method includes sensing illumination level in illumination from the illuminator with a sensor and outputting output proportionate to illumination sensed by the sensor indicative of voltage detected at the voltage input node. The method can include limiting current between the voltage input node and the illuminator.

A circuit comprises an optical coupling including an illuminator optically coupled to an optical sensor to output a voltage from the optical sensor based on intensity of illumination from the illuminator. The circuit includes a voltage input node with a resistance connected in series between the voltage input and a Zener diode. A method includes powering an illuminator with current from a first voltage input node. The method includes sensing illumination level in illumination from the illuminator with a sensor and outputting output proportionate to illumination sensed by the sensor indicative of voltage detected at the voltage input node. The method can include limiting current between the voltage input node and the illuminator.

A power supply system includes an output terminal, a power supply control chip, a power supply switch and a detection device. The power supply control chip is configured to adjust the amount of an input power providing to an electronic device by the power supply device. The power supply switch is configured to control the connection between the power supply device and the power supply control chip. The detection device is configured to detect whether the power supply control chip operates normally. When the power supply control chip operates abnormally, the detection device controls the connection between the power supply device and the power supply control chip through the power supply switch for restarting the power supply control chip. The power supply control chip, the power supply switch and the detection device are disposed in an enclosed space.

A power supply system includes an output terminal, a power supply control chip, a power supply switch and a detection device. The power supply control chip is configured to adjust the amount of an input power providing to an electronic device by the power supply device. The power supply switch is configured to control the connection between the power supply device and the power supply control chip. The detection device is configured to detect whether the power supply control chip operates normally. When the power supply control chip operates abnormally, the detection device controls the connection between the power supply device and the power supply control chip through the power supply switch for restarting the power supply control chip. The power supply control chip, the power supply switch and the detection device are disposed in an enclosed space.

A power control device includes: an output voltage controller configured to control an output voltage based on a feedback voltage corresponding to the output voltage; and an overvoltage protector configured to continue or stop the operation of the output voltage controller based on a first detection result of whether the output voltage has exceeded an output voltage threshold value and a second detection result of whether the feedback voltage has fallen to or below a feedback voltage threshold value.