Patent ID: 8922138

Claim:
A control circuit used for a light emitting apparatus comprising a light emitting element and a switching power supply configured to supply a driving voltage to one end of the light emitting element, and configured to control a switching transistor included in the switching power supply, and to switch on and off a driving current that flows through the light emitting element, the control circuit comprising: a first driver configured to receive a first pulse signal which is pulse width modulated according to a target luminance level of the light emitting element, supplied from a circuit external to the control circuit, and to switch on and off the driving current according to the first pulse signal; an oscillator configured to generate a cyclic signal having a predetermined frequency; a pulse modulator configured to generate a second pulse signal, wherein the second pulse signal transits to an on level that corresponds to an on state of the switching transistor in synchronization with the cyclic signal, and transits to an off level that corresponds to an off state of the switching transistor according to at least one voltage that develops at a node of the light emitting apparatus which is supplied as a feedback voltage; and a second driver configured to switch on and off the switching transistor according to the second pulse signal, wherein the oscillator is configured to be reset according to a first edge which is a transition of the first pulse signal from a first level that corresponds to the off state of the light emitting element to a second level that corresponds to its on state.