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LM317 / LM338 / LM350 VOLTAGE AND CURRENT REGULATOR CALCULATOR

LM317 / LM338 / LM350 VOLTAGE REGULATOR CALCULATOR

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 LM317 / LM338 / LM350 family of three terminal adjustable regulators. This calculator will work for most voltage regulators with a reference voltage (VREF) of 1.25. Typically, the program resistor (R1) is 240 ohms for the LM117, LM317, LM138 and LM150. For the LM338 and LM350, 120 ohms is typically used. However, other values such as 150 or 220 ohms can also be used. Refer to the adjustable regulator datasheets below for more information.

Typical LM317 / LM338 / LM350 Voltage Regulator Schematic
Figure 01: Typical LM317 / LM338 / LM350 Voltage Regulator Schematic

To determine the output voltage, enter values for the program (R1) and set (R2) resistors and hit the "Calculate" button.

NOTE: this online calculator requires that JavaScript be enabled.

R1 (ohms)
 R2 (ohms)
 Output Voltage

LM317 / LM338 / LM350 CURRENT REGULATOR CALCULATOR

You can use this calculator to vary the value of the program resistor (R1) and calculate the output current for the LM317 / LM338 / LM350 family of three terminal adjustable regulators. This calculator will work for adjustable regulators with a reference voltage (VREF) of 1.25.

Typical LM317 1A Current Regulator Schematic
Figure 02: Typical LM317 1A Current Regulator Schematic

To determine the output current, enter values for the program (R1) resistor and hit the "Calculate" button.

NOTE: this online calculator requires that JavaScript be enabled.

R1 (ohms)
 Output Current (Amperes)

3 Terminal Adjustable Regulator Datasheets