A control circuit for a DC-DC converter includes: an output control circuit configured to control an output voltage of a DC-DC converter according to a reference voltage; a reference control circuit configured to control the reference voltage according to an open-circuit voltage of an external power supply coupled to the DC-DC converter; a limiting circuit configured to limit a current flowing from DC-DC converter to an external load; and a stopping control circuit configured to stop operation of the limiting circuit until the reference voltage reaches a given value.