Circuit arrangement for generating switching signal for current controlled switched mode power supply

Abstract

The invention relates to a circuit arrangement for generating a switching signal for a current controlled switched mode power supply, comprising a transformer (Tr), with at least one primary winding (Wp) and at least one secondary winding (Ws), a controlled power breaker (T1), in series with the primary winding (Wp) and a supply DC voltage (VIn), a control circuit (A), for the clocked switching on and off of the power switch (T1) in a cycle with a frequency (f), a current measuring device (M, Rsense) for measuring the value of the current (I>ense) flowing through the power switch (T1) and generating a measured signal (Ssense) as a measure of the measured current value (Isense), a reference signal source (Q) for the generation of a reference signal (Sref), whereby the reference signal (Sref) is a time-independent constant reference signal (S0) and a comparator circuit (V) for the comparison of the measured signal (Ssense) with the reference signal (Sref) and for signalling the control circuit (A) for switching off the power switch (T1) when the measured signal (Ssense) is greater than the reference signal (Sref, Uref). The reference signal source (Q) is connected to a compensation signal source (Q') for the generation of a compensation signal (SKomp) which changes over time, such that the reference signal (Sref) arises from the sum of the constant reference signal (S0) and the compensation signal (SKomp).

Description

technical field [0001] The invention relates to a circuit for generating switching signals for a current-controllable switched-mode power supply device, comprising a transformer comprising at least one primary winding and at least one secondary winding. Background technique [0002] Known circuits of the type on which the present invention is based are available in numerous modifications over the prior art. In this text, for example, reference should be made to "U. Tietze and Ch. Schenk, "Semiconductor Circuit Technology" No. 10, Springer Verlag, Berlin Heidelberg, New York, 1993, p. 456ff. These circuits are basically based on a controllable power switch connected in series with the primary winding to the input DC voltage. The circuit also has a drive circuit that switches the power switch on and off at a clock frequency beat, a current measuring device that measures the current passing through the power switch and generates a measurement signal for measuring the current v...

AI Technical Summary

Problems solved by technology

In this case, if the current intensity exceeds the maximum value, the power switch and / or the load can be easily thermally overloaded and destroyed

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