| 摘要 |
A switched mode power supply includes a switch (T) for clocked application of a variable supply voltage (V) to the primary winding (L1) of a transformer. A current measurement arrangement (MA;R1) provides a current measurement signal (Vs) which is dependent on the primary current flowing through the primary winding. To determine the supply voltage (V) an evaluating circuit (AWS) is connected to the first current measurement arrangement (MA;R1) and weights the time curve of the current (IL) and/or the current measurement signal (Vs), and specifically includes a switching device (R2,C1,I,K;R2,C1,OPV,K,Vref) for preparing a signal dependent on the slope of the measurement signal (Vs) and for comparing this signal with a reference signal (I;Vref).
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