Power control semiconductor device and variable output voltage power supply

A power control semiconductor device, comprising:

• a voltage input terminal to which a DC voltage is input;
• an output terminal;
• a voltage control transistor connected between the voltage input terminal and the output terminal;
• a control circuit that controls the voltage control transistor according to an output voltage of the output terminal;
• a bias circuit that generates a voltage that operates the control circuit based on the DC voltage input to the voltage input terminal;
• and
• a first external terminal and a second external terminal to which a first external input signal and a second external input signal provided from an outside are input, respectively, to control the output voltage,
• wherein the control circuit comprises:
• a voltage divider that divides the output voltage of the output terminal;
• an error amplifier that outputs a voltage corresponding to a potential difference between a predetermined reference voltage and a voltage divided by the voltage divider;
• and
• a logic circuit that generates:
• two or more control signals that changes the voltage divided by the voltage divider, which is input to the error amplifier, according to the first and second external input signals input to the first and second external terminals;
• and
• a signal that stops operation of the bias circuit in response to one of combinations of the first external input signal and the second external input signal, and
• wherein the logic circuit comprises:
• two or more transistors that are turned on/off by the first external input signal and the second external input signal input respectively to the first external terminal and the second external terminal;
• and
• two or more current sources respectively connected in series with the transistors, and
• when operation of the bias circuit is stopped by the signal from the logic circuit, currents of the two or more current sources are interrupted.

A variable output voltage power supply, comprising:

• a power control semiconductor device comprising:
• a voltage input terminal to which a DC voltage is input;
• an output terminal;
• a voltage control transistor connected between the voltage input terminal and the output terminal;
• a control circuit that controls the voltage control transistor according to an output voltage of the output terminal;
• a bias circuit that generates a voltage that operates the control circuit based on the DC voltage input to the voltage input terminal;
• and
• a first external terminal and a second external terminal to which a first external input signal and a second external input signal provided from an outside are input, respectively, to control the output voltage,
• wherein the control circuit comprises:
• a voltage divider that divides the output voltage of the output terminal;
• an error amplifier that outputs a voltage corresponding to a potential difference between a predetermined reference voltage and a voltage divided by the voltage divider;
• and
• a logic circuit that generates:
• two or more control signals that changes the voltage divided by the voltage divider, which is input to the error amplifier, according to the first and second external input signals input to the first and second external terminals;
• and
• a signal that stops operation of the bias circuit in response to one of combinations of the first external input signal and the second external input signal;
• and
• a controller that outputs the first external input signal and the second external input signal to the first external terminal and the second external terminal, respectively,
• wherein the output voltage is changed according to the first external input signal and the second external input signal input to the first external terminal and the second external terminal from the controller.