| 摘要 |
PROBLEM TO BE SOLVED: To improve rising characteristics of an output voltage at activation, of a switching power supply device having a function for reducing a switching frequency to perform current drooping at an overload.SOLUTION: A switching power supply device comprises: a control circuit performing feedback control of a pulse width of a drive signal for switching a switching element depending on an output voltage to make the output voltage be contant at a predetermined voltage level; a frequency reduction circuit provided to this control circuit, and reducing a frequency of the drive signal for switching the switching element to restrict an output current when an overload is detected; and an initial state setting circuit setting the control circuit to an overload detection state over a predetermined time period at activation of the control circuit. In particular, an initial state setting circuit pulling down a CS signal for soft start to a ground potential to inhibit generation of the drive signal, and pulling up a FB (Feedback) signal to a voltage indicating an overload state is provided. |
