# LM317 Current Calculator

# LM317 Current Calculator

## A handy online output current calculator for the LM317, LM338, and other linear voltage regulators

**home**> electric circuit | electronics | general

In our article

**Using the LM317 with LED Lighting**we looked at how the

**LM317T**(and high current equivalent

**LM338T**) can be used to supply a

**fixed**to a load - in the case of the article to

__current__**LED bulbs**.

The output

**current**from the circuit shown above is set using a single

**resistor**according to the following equation:

Resistor Required (Ohms) = 1.25 (Volts) / nominal LED current (Amps) |

Do not forget that the maximum

__continuous__current which can be managed by the LM317T is

**1.5 Amps**, and that is with a decent

**heatsink**fitted (click here to see our article

**LM317T Heatsinking**for more details).

The LM338T is rated at

**5 Amps**of continuous current with 50ms bursts of up to 7 Amps. However with a large heatsink and/or cooling fan it can manage continuous currents of 8 Amps+.

## LM317/LM338 Voltage Calculator

If you would like to use the LM317T or LM338T to output a**fixed**rather than current, click here to visit our

__voltage__**LM317 Voltage Calculator**. We also have a guide to making an Adjustable Voltage LM317 Power Supply here.

Article Last Modified: 22:21, 24th Sep 2014

## Comment on this Article

If you have any comments on this article, please email them to neil@reuk.co.uk.## Related Articles

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LM317T HeatsinkingChoosing a heatsink for use with an LM317T voltage regulator | LM317 Voltage CalculatorA handy online output voltage calculator for the LM317, LM338, and other linear voltage regulators | Using The LM317T With LED LightingUse an LM317T to regulate the current in LED lighting projects | LM2941 1A Low Dropout Adjustable RegulatorFind out about the LM2941 - an adjustable regulator with very low dropout voltage |

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