| 摘要 |
PROBLEM TO BE SOLVED: To provide a DC-DC converter which is used for various kinds of electronic apparatus and supplies a controlled DC voltage to a load having the DC voltage of a battery or the like inputted, and operates with high efficiency even at light load. SOLUTION: In the DC-DC converter which has an input DC power source 1, a switch means 2, a rectifying means 4, an inductor 4, and an output capacitor 5, an output detection circuit 7 detects the output DC voltage, and outputs first voltage Ve1 and second control voltage Ve2 higher by a specified value than the first control voltage Ve1, and an oscillating circuit 8 outputs an oscillating voltage Vc, and a control device circuit 9 outputs a drive signal Vg for turning on the switch means 2 when Vc<Ve1, and the oscillating circuit 8 gentles the inclination of the increase and decrease in the oscillating voltage Vc when Vc>=Ve2, whereby the off-period of the switch means 2 is extended more the lighter the load is, thus reducing the switching loss.
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