HYSTERESIS COMPARATOR CIRCUIT AND WAVEFORM GENERATION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To improve power conversion efficiency at the time of a light load in a DC/DC converter by installing first - third switching elements which can be turned on/off in accordance with an outer signal and first and second capacitors connected to the respective switching elements. SOLUTION: In a charging/discharging operation when the first and the third switching elements SW1 and SW3 of a hysteresis comparator circuit become closed states and a second switching element SW2 becomes an open state, a first capacitor C2 executes a charging operation when SW1 is in the closed state and consumption current I2 is supplied from a reference voltage source Vref 30. Thus, the charge of charge quantity Q2 is charged. Since SW2 is in the open state and SW3 is in the closed state, a second capacitor C3 executes the discharging operation. Thus, charge quantity Q3 becomes zero. Consequently, reference voltage VM being the potential of the (-) input terminal side of the hysteresis comparator 11 is boosted to a potential Vref with a prescribed time constant.