| 摘要 |
PURPOSE:To improve the overcurrent drooping characteristic and to make the device small-sized and low-cost by adding an overcurrent protecting circuit where the second reference voltage set to a value lower than the first reference voltage and an input voltage are compared with each other in the second voltage detecting circuit. CONSTITUTION:An input DC voltage IN passes smoothing circuits 1-3 and is subjected to switching control in transistors TRs 4 and 5 and passes a transformer 6 to output an AC voltage. This AC voltage passes a saturable reactor 9, etc. and passes a rectifying circuit 10 and a smoothing circuits 11-13 and is outputted OUT. The output of the rectifying circuit 10 is compared with the first reference voltage 15 in a comparator 14, and the control winding of the saturable reactor 9 is controlled by this error signal, and the fluctuation of the output OUT is so suppressed that it becomes a constant voltage. In this case, the overcurrent protecting circuit (surrounded with a broken line in the figure) is added where the input DC voltage IN is divided by a resistance 23 and the second reference voltage set to a value lower than the first reference voltage 15 and the output of the rectifying circuit 10 are compared with each other in a comparator 22, thus making the drooping start point of the overcurrent uniform. |
