| 摘要 |
<p>A switching power supply such that the step-up ratio of when the power factor is improved does not increase, and the conversion efficiency can be improved. When the error voltage Ver outputted from a conductance amplifier (23) increases over a reference voltage Vref2, a switching signal of high level is outputted from a comparator (59) to a FET (57) to turn on the FET (57). Therefore a resistor (56) is bypassed, and as a result a reference voltage Vref1 inputted into the conductance amplifier (23) is changed from a reference voltage Vref1-1 to Vref1-2 of lower level. Further, since the variation of the error voltage Ver outputted from the conductance amplifier (23) decreases, the output voltage Vout also decreases.</p> |
