Abstract: A power supply circuit includes an output transistor which adjusts an input voltage and generates an output voltage, an error amplifier which generates a control voltage for the output transistor according to a difference between a feedback voltage corresponding to the output voltage and a reference voltage, an overcurrent protection circuit which controls the error amplifier according to a result of monitoring the control voltage and controls the control voltage so as to drop the output voltage, and an undershoot detection circuit Which detects an undershoot of the output voltage and controls the control voltage for the output transistor so as to suppress the output voltage from dropping.

Abstract: The present invention includes an output transistor (M7) which generates an output voltage (VOUT); an error amplifier which generates a control voltage (VG7) for the output transistor (M7) according to a difference between a feedback voltage (VFB1) corresponding to the output voltage and a reference voltage (VREF1); an overcurrent protection circuit (16) which controls the error amplifier according to a result of monitoring the control voltage (VG7) so as to drop the output voltage; and an undershoot detector (15) which detects an undershoot of the output voltage and controls to increase a drive force of the output transistor (M7).