LM317 Current Expanding Circuit 3

Published:2011/8/1 11:02:00 Author:Robert | Keyword: Current, Expanding | From:SeekIC

The picture shows the LM317 current expanding circuit 3. This picture is the parallel current expanding circuit's principle circuit. It is made up of two adjustable voltage regulators LM317. The input port's voltage V1=25V and the output current Io=Io1+Io2=3A. The output voltage's adjustable range is 1.2V to 22V. In this LM317 current expanding circuit, the integrated operational amplifier 741 is used to balance the two voltage regulator's output current. If the LM317-1's output current Io1 is larger than the LM317-2's output current Io2, the voltage drop on resistor R1 would increase, the operational amplifier's in-phase voltage Vp (=V1-I1R1) would decrease and the operational amplifier's output port's voltage Vao would decrease. By the adjusting port adj1 it would make the output Vo decrease and make the output current Io1 decrease so that it would be balanced. Otherwise it would be the same principle. By adjusting the resistor R5 it would adjust the output voltage's value.



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