| 摘要 |
A step-down switching regulator of synchronous commutation type using a hysteresis comparator used for reducing the ripple of the output voltage when the load is light. The step-down switching regulator (200) comprises a control circuit (100) for turning on/off the switching element. The control circuit (100) has a hysteresis comparator (10), a light-load detecting circuit (50), and a driver circuit (30). The hysteresis comparator (10) compares the detection voltage Vout' corresponding to the output voltage Vout of the step-down switching regulator (200) with first and second threshold voltages Vth1, Vth2 (Vth2<Vth1). The light-load detecting circuit (50) detects if the load is light. The driver circuit (30) turns on/off the switching element according to a pulse signal SIG1 outputted from the hysteresis comparator (10). When the light-load detecting circuit (50) detects that the load is light, the hysteresis comparator (10) shifts the second threshold voltage Vth2 by a predetermined voltage width toward the high potential side.
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