| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a ripple control type switching power supply device that has an adaptive on-time function implemented on a control circuit without increasing the number of external terminals. <P>SOLUTION: In the ripple control type switching power supply device having the control circuit (20) for controlling on/off a driving switching element for applying a current to an inductor, the control circuit includes: an emulation voltage generation circuit (21) for smoothing a potential at a node connecting the driving switching element and the inductor to generate an emulation voltage corresponding to an output voltage; timing means (22) for measuring a time corresponding to an input voltage and the emulation voltage; a voltage comparison circuit (23) for comparing a feedback voltage with a predetermined voltage; and a control pulse generation circuit (24) for generating a control pulse having a pulse width corresponding to the time measured by the timing means on the basis of an output of the timing means and an output of the voltage comparison circuit, and is configured to maintain a constant period by changing the pulse width of the control pulse with changing input voltage. <P>COPYRIGHT: (C)2013,JPO&INPIT |
