Patent ID: 6882133

Claim:
A DC/DC converter control circuit capable of switching internal operation state between active state and non-active state, the DC/DC converter control circuit comprising: a frequency setting terminal for externally connecting an external impedance element to a point between the frequency setting terminal and external predetermined voltage; a bias section for getting the external impedance element biased, the bias section being connected to the frequency setting terminal; and an oscillation driving section for controlling oscillation frequencies depending on an impedance value of the external impedance element, the oscillation driving section being connected to the external impedance element through the bias section; wherein the DC/DC converter control circuit further comprises a control section for controlling the internal operation, the control section being activated based on a signal from the oscillation driving section, an auxiliary activator section for keeping the bias section in an active state when the internal operation is in a non-active state, and the oscillation driving section starts-up when a path between the frequency setting terminal and the external predetermined voltage which passes through the external impedance element is closed to be conductive by an external switching section which opens and closes the path.