Voltage regulator
View Patent ↗Provided is a voltage regulator including an overcurrent protection circuit using a simple circuit. The voltage regulator includes the overcurrent protection circuit including: a first sense transistor having a gate connected to an output terminal of an error amplifier circuit and a drain connected to a sense resistor; a second sense transistor having a gate connected to the output terminal of the error amplifier circuit; and a control transistor having a gate connected to an output terminal of a control circuit, a source connected to a drain of the second sense transistor, and a drain connected to the sense resistor, in which the control transistor is turned on in response to a detection signal output by the control circuit until a reference voltage exceeds a predetermined voltage.
1. A voltage regulator, comprising:
an output transistor for outputting a current depending on a control voltage to an output terminal;
an error amplifier circuit for comparing a reference voltage output from a reference voltage circuit and a divided voltage obtained by dividing an output voltage of the output terminal by a resistor to output the control voltage to the output transistor;
an overcurrent protection circuit for outputting a control signal to the output transistor when an output current output by the output transistor reaches a predetermined current limit value; and
a control circuit for outputting a detection signal to the overcurrent protection circuit until the reference voltage exceeds a predetermined voltage,
wherein the overcurrent protection circuit comprises:
a first sense transistor having a gate connected to an output terminal of the error amplifier circuit and a drain connected to a sense resistor;
a second sense transistor having a gate connected to the output terminal of the error amplifier circuit; and
a control transistor having a gate connected to an output terminal of the control circuit, a source connected to a drain of the second sense transistor, and a drain connected to the sense resistor, and
wherein the control transistor is turned on in response to the detection signal output by the control circuit.
2. A voltage regulator according to claim 1 ,
wherein the control circuit comprises:
a transistor having a source connected to a ground and a gate connected to an output terminal of the reference voltage circuit;
a resistive element having one end connected to a power supply voltage and another end connected to a drain of the transistor; and
an inverter having an input terminal connected to a connection node between the transistor and the resistive element, and
wherein the transistor has a threshold voltage that is higher than a threshold voltage of a transistor which forms a differential pair with the error amplifier circuit and is connected to the output terminal of the reference voltage circuit.
3. A voltage regulator according to claim 1 , wherein the overcurrent protection circuit comprises a drooping overcurrent protection circuit, a drooping fold-back overcurrent protection circuit, or a drooping overcurrent protection circuit and a drooping fold-back overcurrent protection circuit.
4. A voltage regulator according to claim 2 , wherein the overcurrent protection circuit comprises a drooping overcurrent protection circuit, a drooping fold-back overcurrent protection circuit, or a drooping overcurrent protection circuit and a drooping fold-back overcurrent protection circuit.