Patent ID: 7831851

Claim:
A switching regulator converting an input voltage into a predetermined constant voltage and outputting the constant voltage from an output terminal, the switching regulator comprising: a switching transistor controlling output of the input voltage by switching in accordance with a control signal input to a control electrode; a smoothing circuit part configured to smooth an output voltage of the switching transistor and output the smoothed output voltage to the output terminal; a control circuit part configured to control the switching of the switching transistor in synchronization with an externally input clock signal so that a voltage at the output terminal is the predetermined constant voltage; and a clock signal detector circuit part configured to detect presence or absence of inputting of the clock signal, the clock signal detector circuit part comprising: an edge detector circuit configured to detect at least one of a rising edge and a falling edge of signal level of the clock signal and output a pulse of a predetermined pulse width for the detected at least one of the rising edge and the falling edge every time the at least one of the rising edge and the falling edge is detected; an integrating circuit configured to charge a capacitor with a preset time constant; a switching device configured to release an electric charge stored in the capacitor upon the outputting of the pulse from the edge detector circuit; and a binarizing circuit configured to generate a control signal to perform operation control of the control circuit part by converting a terminal voltage of the capacitor into a binary signal, and output the generated control signal, wherein upon detecting stoppage of the inputting of the clock signal, the clock signal detector circuit part causes the control circuit part to stop operating and perform a standby operation for reducing power consumption and thereby to turn off the switching transistor, and wherein the switching transistor, the control circuit part, and the clock signal detector circuit part are integrated into a single IC.