摘要 |
<p>A switching power supply apparatus comprises a transformer (T) having primary winding (T1) and at least two secondary windings (T2, T3), a first switching element (Q1) connected in series with the primary winding (T1), a control circuit (CT) for controlling the output from the first switching element (Q1) by control of the on-time thereof, a rectification circuit (Ds1, Ds2) for rectifying at least two outputs from the secondary windings (T2, T3), an output voltage detection circuit (DT) for detecting the output voltages (Vo1, Vo2) and feeding back the output voltages as a control signal for control of the on-time to the control circuit. The output voltage detection circuit (DT) comprises a control signal formation section (ZD1) in which the control signal for the on-time is formed, corresponding to a voltage at a voltage comparison terminal (Vr), and plural voltage detectors (R2, R4) connected between the at least two outputs of the secondary windings (T2, T3) and the voltage comparison terminal, respectively. <IMAGE></p> |