Voltage regulator with turn-off assist
View Patent ↗To provide a voltage regulator capable of securely being turned off even if the regulator is used under a high temperature and an impedance of an external load is large. A voltage regulator is provided, which includes a voltage divider circuit that can divide a potential difference between an output voltage terminal and a reference terminal, wherein when the voltage divider circuit inputs an on signal, the voltage divider circuit outputs a constant voltage between the output voltage terminal and the reference terminal, and wherein when the voltage divider circuit inputs an OFF signal, the voltage divider circuit can reduce the impedance thereof.
1. A voltage regulator for converting an input voltage into a regulated output voltage, comprising: external connection terminals including an output voltage terminal for outputting the regulated output voltage, a reference terminal, and a control signal input terminal for inputting a control signal; a voltage divider circuit for dividing the regulated output voltage and outputting a divided voltage; an error amplifier controlled by the control signal for comparing the divided voltage with a reference voltage and controlling a level of the regulated output voltage based on the comparison result when the control signal has a first value; a transistor connected in parallel with the voltage divider circuit; and a resistor connected in series to the transistor and having a resistance value smaller than that of the voltage divider circuit so that the transistor is turned on when the control signal has a second value so as to pull down the voltage at the output terminal to the reference terminal through the voltage divider circuit.
2. A voltage regulator circuit comprising: external connection terminals including an input voltage terminal for receiving an input voltage, an output terminal for outputting a regulated output voltage, a reference potential terminal, and a control terminal for inputting a control signal; an output circuit connected to the output terminal and having a variable impedance value; a reference voltage generating circuit for generating a reference voltage; a voltage divider circuit for dividing the output voltage and outputting a divided voltage; an error amplifier circuit for comparing the divided voltage and the reference voltage and adjusting the impedance of the output circuit based on the comparison result so that the divided voltage becomes equal to the reference voltage when the control signal has a first value; a logic circuit connected to the control terminal for controlling the error amplifier circuit to increase the impedance of the output circuit when the control signal has a second value; and a transistor connected in series to a resistor having a resistance value smaller than that of the voltage divider circuit, the transistor being connected in parallel with the voltage divider circuit and being turned on when the control signal has the second value so that the output terminal is pulled down to the reference potential terminal through the impedance of the voltage divider circuit.
3. A voltage regulator circuit comprising: external connection terminals including an input voltage terminal for receiving an input voltage, an output voltage terminal for outputting a regulated output voltage, a reference potential terminal, and a control terminal for inputting a control signal; an output circuit connected to the output terminal and having a variable impedance value; a reference voltage generating circuit for generating a reference voltage; a voltage divider circuit for dividing the output voltage and outputting a divided voltage; an error amplifier circuit for comparing the divided voltage and the reference voltage and adjusting the impedance of the output circuit based on the comparison result so that the divided voltage becomes equal to the reference voltage when the control signal has a first value; a logic circuit connected to the control terminal for controlling the error amplifier circuit when the control signal has a second value to increase the impedance of the output circuit; a resistor connected in series to the voltage divider circuit and having a resistance value smaller than that of the voltage divider circuit; and a transistor connected in parallel with the voltage divider circuit, the transistor being turned on when the control signal has the second value so that the output terminal is pulled down to the reference potential terminal through the impedance of the voltage divider circuit.