| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching regulator integrated circuit device for constituting an overvoltage protecting circuit without adding external terminals and external components, and to provide a switching power supply. SOLUTION: A drain voltage of an n-channel MOSFET Q1 is input from an detection voltage (VD) input terminal 21, divided by resistors R2, R3 and compared with a reference voltage Vref1. A capacitor C3 is charged by a constant current for a predetermined time when an output from a comparator 23 exceeds the reference voltage. When the capacitor C3 is charged by continuous charge pulses from a charge pulse generating circuit 24 until its voltage exceeds a threshold voltage of an inverter 27, an RS flip-flop 29 is set and outputs a signal for stopping a switching operation through an inverter 30. After the switching operation stops, overvoltage protection is continuously implemented, and an unstable operation can be prevented even if the preset reference voltage Vref1 is temporarily exceeded due to noise. COPYRIGHT: (C)2005,JPO&NCIPI
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