| 摘要 |
PURPOSE:To facilitate to fabricate IC without increasing the number of elements, by controlling the conduction of a frequency divider which sends out two signals that are 180 deg. out of phase with the aid of the output of an oscillator whose duty ratio can be varied corresponding to the output voltage. CONSTITUTION:Pulse outputs which are 180 deg. out of phase to each other are obtained by dividing the pulse signal from a variable-duty-ration oscillator 24 comprising a non-stable multivibrator into 1/2 by a frequency divider 25 comprising an FF at the duty ratio of 50%. Both outputs are applied to input terminals 8 and 9 of transistor switches 1 and 2 of a push-pull type DC-DC converter 15 via transistor switches 26 and 27, respectively. When the load varies, the duty ratio is controlled by executing negative feedback from a control input terminal 11 to the oscillator 24. Therefore, the number of elements can be reduced and IC can be economically fabricated. |
