| 摘要 |
PROBLEM TO BE SOLVED: To prevent the increase of the package size of an integrated circuit without increasing the number of terminals of the integrated circuit for setting up the operation delay time of a protective function, in a switching power supply having a protective function of protecting a power supply from abnormal states including an output short-circuit. SOLUTION: A signal from a difference amplification circuit 2 that amplifies a difference between an output voltage and a set voltage is inputted into a feedback terminal Tfb of an integrated power supply control circuit 1, to control drive pulses outputted to a power transistor PT1 by a pulse width control circuit 12. Furthermore, a series circuit of a capacitor C2 and a resistor R1 for delaying the operation of an overload protective circuit 13 and a comparator IC11 having a reference voltage are connected to the connection point (Tfb) of the difference amplification circuit 2 and the pulse width control circuit 12 to operate the overload protective circuit 13 by an output of the comparator IC11. COPYRIGHT: (C)2008,JPO&INPIT
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