LM 317 Calculator



Calculate LM317 Resistor Values

This calculator is used to find the value of the voltage adjustment resistor required to set the output of an LM317 to a specified level. Typically R1 is 220 ohms or 240 ohms, but it could be some other value. Check the Data Sheet for more information regarding this. Select a value for R2 and hit the Calculate button. The LM317 output value is reported in volts.

Note: The input voltage to the LM317 must be at least 1.5v greater than the output voltage.

Note2: You can get ridiculous values with the right combination of R1 and R2. Please note the actual capability of the device from the Data Sheet.

LM317 Tutorial: http://www.netwak.com/electronics/lm317/tutorial.html

R1 resistor

R2 resistor

Output Voltage