Patent ID: 7777474

Claim:
A switching type DC-DC converter for converting an input voltage and generating an output voltage, the DC-DC converter comprising: an adjustment resistor; a control circuit that generates a control signal and includes an external terminal to which the adjustment resistor is externally connected; and a switching transistor connected to the control circuit and turned on or off in accordance with the control signal; wherein the control circuit includes an oscillator that generates an oscillation signal, with the control circuit generating the control signal based on the oscillation signal and a signal that is in accordance with an output voltage or output current of the DC-DC converter, wherein the oscillator includes: a first transistor to which the input voltage is provided; a second transistor arranged between the first transistor and the external terminal; and a third transistor, which is coupled to a first node between the first transistor and the second transistor, to a second node between a first resistor to which the input voltage is provided and a transistor coupled to around, and to a second resistor coupled to ground; and the oscillator monitors a first amount of current flowing through the external terminal of the control circuit by the third transistor monitoring a state of the first node and generates the oscillation signal in a cycle that is in accordance with the monitoring result and resistance values of the first resistor and the second resistor.