LM317 Voltage Regulator Calculator

Your details

Choose what you want to solve for. In voltage-regulator modes R1 is the upper resistor (between OUT and ADJ); R2 is the lower resistor (between ADJ and GND).
The three variants share the same resistor formula but differ in maximum output current.
The resistor between the OUTPUT pin and the ADJ pin. TI recommends 240 Ω as the standard value to keep minimum load current around 5 mA.
Ω
The resistor between the ADJ pin and GND. Increasing R2 raises the output voltage.
Ω
The unregulated DC supply fed into the INPUT pin. Must be at least 3 V above Vout for the LM317 to regulate correctly.
V
The current drawn by your load. Used for power-dissipation and efficiency calculations.
A
Output voltage (Vout)High dissipation - heatsink required
5.036V

Regulated DC output voltage

Power dissipated by IC3.48W
Efficiency0.4%
Heatsink needed?Yes - high dissipation (> 2 W), use a heatsink
Dropout marginOK - margin is 6.96 V (need >= 3 V)
3.48 W
No heatsink<0.5Optional0.5-1Heatsink recommended1-2Heatsink required2+

Output voltage: 5.036 V

  • The IC dissipates 3.48 W as heat. Add a heatsink to prevent thermal shutdown.
  • Efficiency is 42.0%. Linear regulators convert the Vin - Vout gap directly into heat, so a lower input voltage means higher efficiency.

Next stepAdd a 0.1 uF ceramic capacitor on the input and a 1 uF tantalum capacitor on the output to suppress oscillations.

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