LM317 Calculator V2.0

The LM317 is one in LM117 series of adjustable 3 terminal positive voltage regulator capable of supplying in excess of 1.5 amps over an output range of 1.25 to 37 volts. The device also has built in current limiting and thermal shutdown which makes it essentially blow-out proof.Output voltage is set by two resistors R1 and R2 connected as shown below. The voltage across R1 is a constant 1.25 volts and the adjustment terminal current is less than 100uA. The output voltage can be closely approximated from Vout=1.25 * (1+(R2/R1)) which ignores the adjustment terminal current but will be close if the current through R1 and R2 is many times greater.The example below shows a LM317 used as 11.8 volt regulator. The R1 and R2 use standard ±1% resistor.
To use this software you need to enable Javascript in your browser.(works fine in IE7 and Firefox 3)