| 摘要 |
PURPOSE:To prevent the second DC output of a switching power source from decreasing by enhancing the reference voltage of a first DC output at no load time. CONSTITUTION:An output 1 is compared by a voltage comparator 4 with the output of a reference voltage generator 3, and a switching controller 5 controls the driving pulse width of a switching transformer 6 to be stabilized on the basis of a compared result. An output 2 is stabilized by controlling the unstabilized DC output obtained from another secondary winding of the transformer 6 by a dropper 7. A CPU 8 controls a load circuit 9, and feeds a signal to the generator 3 at no load time. The generator 3 receives the signal to enhance the output voltage to the comparator 4. Accordingly, when the output 1 is at no load time, the driving pulse width of the transformer 5 does not extremely decreases to eliminate the decrease of the output 2.
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