Patent ID: 8508963

Claim:
A step-down switching regulator comprising: a switching element formed of a high-voltage NMOS transistor and turned on and off based on a control signal input to a gate, configured to charge an inductor with an input voltage not smaller than a withstand voltage of a low-voltage MOS transistor but smaller than a withstand voltage of a high-voltage MOS transistor input to an input terminal; a rectifier configured to discharge the inductor when the switching element is turned off to stop charging the inductor; a voltage generator configured to generate a predetermined first constant power supply voltage having a predetermined voltage value not greater than a withstand voltage of the low-voltage MOS transistor; a first drive circuit formed of a low-voltage MOS transistor and configured to receive the predetermined first constant power supply voltage from the voltage generator and turn on and off the switching element based on the input control signal; a capacitor connected in parallel with the first drive circuit and configured to store charge from the voltage generator to supply power to the first drive circuit, one end of which is connected to a junction node between the switching element and the inductor and the other end of which is supplied with the first constant power supply voltage from the voltage generator; and a controller configured to generate the control signal for turning on and off the switching element and output the control signal to the first drive circuit, such that the input voltage is converted into a predetermined constant voltage to be output from an output terminal.