Peak current controlled type driver converter

摘要

PURPOSE:To always stably operate a switching element and hence a converter by applying a clock signal delayed at the time of a light load to driving means, and increasing the width of ON time of a drive signal. CONSTITUTION:A load current of the secondary side of a transformer 2 is detected by a resistor Rc. If a load becomes light, an operational amplifier 14 outputs a signal indicating it to open a gate 12. A delay clock signal from a delay circuit 11 is applied to a third circuit 13, and applied together a peak current detection voltage Vsense corresponding to a peak current converted by a resistor Rsense to the reset terminal of a flip-flop 5 through a comparator 4. Accordingly, a drive signal Q from the flip-flop 5 becomes an OFF state, and a switching element 1 is turned OFF. Thus, the operation of a converter does not become unstable. That is, the width of the ON time of the signal Q becomes large, and the converter is always stably operated.