| 摘要 |
A flyback converter comprising: a transformer (6) having a primary winding (4) and a switching transistor (2), arranged in series therewith; control means (14) for closing the switching transistor (2) during a primary interval and opening the switching transistor (2) during a secondary interval in response to a control signal (UC), an auxiliary winding (12) for generating a feedback signal (UFB), measurement means (20) for unidirectionally measuring the feedback signal (UFB), a comparator (16) and a logic circuit (18) for deriving from the feedback signal (UFB) a first timing signal (TM1) which is representative of the secondary interval; comparison means for comparing the unidirectionally measured feedback signal (IFB) with a reference signal (IR) during the secondary interval, and an integrator (28) for generating the control signal (UC) in response to the comparison. The switched-mode power supply further comprises a logic circuit (32) for generating a second timing signal (TM2) having a starting instant which falls within the primary interval having an end instant which at least does not precede the end instant of the secondary interval. A first time-selective element (26) transfers the reference signal (IR) under command of the first timing signal (TM1), and a second time-selective element (30) transfers the unidirectionally measured feedback signal (IFB) under command of the second timing signal (TM2). As a result of this, the output voltage of the flyback converter is not affected by errors which are caused by a delay in the generation of the first timing signal (TM1). |
