The LM / LM / LM voltage regulators are exceptionally easy to use, requiring only two external resistors to set the regulated output voltage. You can expect performance of both the line and load regulation using the LM / LM / LM adjustable voltage regulators over. Below is our automated voltage calculator for the LM and LM regulators. Simply enter your target output voltage Vout and chosen value for R1 ( to. You can use this calculator to vary the value of the program resistor (R1) and output set resistor (R2) and calculate the output voltage for the LM / LM / LM family of three terminal adjustable regulators.