| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply device that stably controls turning on/off of a main switching element by reducing the effect of delay of a PWM comparator and performing ideal pulse width modulation.SOLUTION: A switching control circuit 38 for controlling turning on/off of a main switching element 12 includes an error amplification circuit 40 for outputting an error amplification voltage Ver, a ramp wave generation circuit 42 for outputting a ramp wave voltage Vram, a PWM comparator 22 and a PWM auxiliary circuit 44. The error amplification circuit 40, the ramp wave generation circuit 42 and the PWM auxiliary circuit 44 output the error amplification voltage Ver, the ramp wave voltage Vram and a predetermined drive voltage Vdr, respectively. The PWM comparator 22 compares the error amplification voltage Ver on which the drive voltage Vdr is superimposed with the ramp wave voltage Vram. At the timing when the difference between the voltages of a pair of input terminals of the PWM comparator 22 decreases, the drive voltage Vdr instantaneously inverts the magnitude relationship between the voltages of the input terminals. |
