| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply device in which circuit constitution is simple, and a circuit scale is also small; and which prevents generation of subharmonic oscillation in a pulse signal for current mode control, and accurately controls an output voltage even if a CR filter is provided between a current detecting resistor and a current detecting terminal Tis, in the switching power supply device of the current mode control. SOLUTION: The switching power supply device includes: a voltage detector to detect the output voltage; a current detector to detect a current flowing through a power transistor of a switching element; a control unit to control duty of an "on" period of the power transistor comparing a voltage detection signal from the voltage detector with a current detection signal from the current detector; and a slope compensation circuit 12 to compensate a rate of change of the voltage detection signal by a slope compensation signal. The slope compensation circuit 12 subtracts the slope compensation signal from the voltage detection signal to output to a PWM comparator 14. COPYRIGHT: (C)2008,JPO&INPIT
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