Abstract: A switched-mode power supply (200, 300, 400) comprises a primary side, a secondary side and a transformer (103, 303, 403) therebetween. An output on the secondary side delivers an output voltage and an output current to a load. An output voltage control circuit (110, 113, 801) keeps the output voltage at a first level, corresponding to a first output current value. A circuit element (201, 301, 401) integrates over time a voltage obtained from the transformer (103, 303, 403) and produces a signal indicative of the integrated voltage, corresponding to a second output current value that is smaller than the first output current value. An output voltage modifier (113, 601, 801) responds to the signal by changing the output voltage from the first level to a second level.

Abstract: A switched-mode power supply (200, 300, 400) comprises a primary side, a secondary side and a transformer (103, 303, 403) therebetween. An output on the secondary side delivers an output voltage and an output current to a load. An output voltage control circuit (110, 113, 801) keeps the output voltage at a first level, corresponding to a first output current value. A circuit element (201, 301, 401) integrates over time a voltage obtained from the transformer (103, 303, 403) and produces a signal indicative of the integrated voltage, corresponding to a second output current value that is smaller than the first output current value. An output voltage modifier (113, 601, 801) responds to the signal by changing the output voltage from the first level to a second level.

Abstract: In order to adjust the output voltage and output current of a galvanically isolated switched-mode power supply, on the primary side there is formed an auxiliary voltage (15) proportional to the secondary voltage, and said auxiliary voltage is studied by means of a window comparator, so that when the auxiliary voltage is within the reference window, there is applied fixed power adjustment, and when the auxiliary voltage falls outside the reference window (>max, <min), the quantity of electric power fed in by the isolation transformer of the primary side is restricted. Most advantageously the auxiliary voltage is formed by means of an auxiliary coil (12b) contained in the isolation transformer, and the reverse threshold voltages of two zener diodes represent the limit values of the reference window.