Patent ID: 7368884
Filing Date: 2008-05-06
Classification: H05B

Abstract:
1. A control circuit of a DC/DC converter for supplying a driving voltage to a light emitting element, said control circuit comprising: a hysteresis comparator which compares a detection voltage that corresponds to the output voltage of said DC/DC converter with two threshold voltages, and outputs a first-level comparison signal when the detection voltage is smaller than the lower threshold voltage, and outputs a second-level comparison signal when the detection voltage is greater than the lower threshold voltage; and a switching control unit which controls the switching operation of a switching element included in said DC/DC converter according to the comparison signal output from said hysteresis comparator as a reference signal, and instructs the switching element of said DC/DC comparator to perform switching operation during a period when the comparison signal is at the first level, and suspends the switching operation of the switching element of said DC/DC comparator during a period when the comparison signal is at the second level, wherein light emission of the light emitting element is inhibited during a period when the comparison signal is at the first level, and wherein light emission of the light emitting element is permitted during a period when the comparison signal is at the second level.