Patent ID: 7046524

Claim:
A power supply device having several switch-mode power supplies connected in parallel to supply at least one load ( 32 ), each switch-mode power supply generating an output current I 0 and an output voltage U 0 (I 0 , R L ) that is a function of the output current I 0 and a load resistance R L , and having a control device for each switch-mode power supply, wherein the control device has a first stage ( 50 ) having a P element ( 54 ) that receives a P element input voltage which is derived from the output voltage U 0 (I 0 , R L ), and generates a P element control voltage U VS , that is used to control the respective switch-mode power supply, the first stage being active when 0≦I 0 ≦I 0P , a second stage ( 60 ) having a current imaging circuit which reproduces the output current I 0 of the respective switch-mode power supply and generates an output current control voltage U P which is used to control the respective switch-mode power supply, the second stage being active when I 0P ≦I 0 ≦I 0S , and a third stage ( 70 ) having an amplifier circuit ( 74 ) which amplifies a signal proportional to the output current I 0 and generates an amplified output current control voltage m·U S which is used to control the respective switch-mode power supply, the third stage being active when I 0S ≦I 0 ≦I K , wherein I 0P is a first threshold value of the output current I 0 ; I 0S is a second threshold value of the output current I 0 ; and I K characterizes a short circuit current limitation.