Switching regulator capable of efficient control at control mode change

A semiconductor device employing a switching regulator, the switching regulator comprising:

• a switching transistor configured to switch in accordance with a control signal;
• an inductor configured to store charge from an input voltage by switching the switching transistor;
• a comparator configured to compare a voltage at a connecting node of the switching transistor and the inductor with a predetermined voltage that indicates an excitation energy of the inductor becoming zero, and generated binary signal indicating a comparison result;
• a detector configured to detect a voltage difference between an output voltage at an output terminal and a predetermined reference voltage, and output a detection signal;
• a pulse generator configured to generate a pulse signal having a predetermined pulse width to switch the switching transistor on/off in VFM control mode;
• and
• a controller configured to determine the output voltage, and to select either VFM control mode or PWM control mode with the switching transistor to make the output voltage a predetermined constant voltage,
• wherein the controller changes the control mode from the VFM control mode to PWM control mode when the controller determines that the output voltage does not change while the pulse generator is outputting the pulse signal in the VFM control mode based on the output signal of the detector.