| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power circuit which can reduce a ripple current. SOLUTION: If a switching element 11 on power source side is OFF and a switching element 12 on synchronization side is ON, a current flowing to the switching element 12 on synchronization side decreases with the passage of time, and the timing of its getting in the range of zero detection is detected by a detector 19. This circuit controls the switching element 12 on synchronization side to break with this timing. This switches on the switching element 11 on power source side after break of the switching element 12 on synchronization side. The switching element 12 on synchronization side breaks the lower limit of the ripple current changing with the passage of time, and it is the current value at the time t12 when the switching element 11 on power source side is switched, and it is in the vicinity of the current value becoming zero. An average load current flowing to a coil 13 is middle between the lower limit and the upper limit of the ripple current changing with the passage of time, and also the change of the ripple current is reduced to about twice the average load current or thereabouts. COPYRIGHT: (C)2005,JPO&NCIPI
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