LM317 voltage regulator: Pinout, CALCULATOR and circuits

In the event, we need to build a variable DC power supply that output of 1A and can adjust up to about 30V.
Most people will use LM317 because of high-efficiency, easy to apply and cheaper

Description

It has an adjustable 3-terminal positive voltage regulator designed to supply more than 1.5 A of load current with an output voltage adjustable over a 1.2V to 37V range.

It has an internal current limiting, temperature detects shutdown and safe area compensation.

LM317 pinout

LM317 Pinout on TO-220
Figure 1: LM317 pinout on TO-220

Look:

LM317 pinout
Connection Diagram various LM317 Pinout

LM317T on TO-220: output 1.5A
LM317L on TO-92: output 100mA
LM317K on TO-3: output 1.5A
LM317 on DPARK: output 1.5A

Basic Features

  • Output current in excess of 1.5A
  • Output-Adjustable between 1.2V and 37V
  • Internal Short-Circuit Current Limiting or Output is short-circuit protected
  • Internal Thermal Overload Protection or Current limit constant with temperature
  • Output-Transistor Safe Operating Area Compensation
  • TO-220 Package like 2SC1061 transistors.
  • There are 1% output voltage Durability
  • There are max. 0.01%/V line regulation(LM317), and 0.3% load regulation (LM117)
  • There are 80 dB ripple rejection

typical application of LM317
Figure 2 the basic circuit diagram

Basic circuit diagram

If the power supply filter has distance from IC-regulator too much. Tt should insert Ci to lower noise before IC-input.

Next in the figure circuit. The Co is not needs if you do not high-efficiency, but we put it better.  It will keep lower an output ripple.

As Iadj is controlled to less than 100uA, the little error Unimportant in most applications.

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

LM317 calculator

This calculator will work for most DC 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.

Some said Iadj is very low current.


So, we may reduce it down. To be shorter and easy.

Vout = 1.25V x {1+R2/R1}

Which is better?

For example:
You use R1 = 270 ohms and R2= 390 ohms. It causes output is 3.06V

Is it easy? If you have voltages choice with most resistors. In local stores near you.

look at the list:

Output Voltage with R1 and R2 List

1.43V : R1 = 470Ω, R2 = 68Ω
1.47V : R1 = 470Ω, R2 = 82Ω
1.47V : R1 = 390Ω, R2 = 68Ω
1.51V : R1 = 330Ω, R2 = 68Ω
1.51V : R1 = 390Ω, R2 = 82Ω
1.52V : R1 = 470Ω, R2 = 100Ω
1.53V : R1 = 390Ω, R2 = 82Ω
1.56V : R1 = 330Ω, R2 = 82Ω
1.57V : R1 = 270Ω, R2 = 68Ω
1.57V : R1 = 470Ω, R2 = 120Ω
1.57V : R1 = 390Ω, R2 = 100Ω
1.59V : R1 = 390Ω, R2 = 100Ω
1.60V : R1 = 240Ω, R2 = 68Ω
1.63V : R1 = 330Ω, R2 = 100Ω
1.63V : R1 = 270Ω, R2 = 82Ω
1.64V : R1 = 390Ω, R2 = 120Ω
1.64V : R1 = 220Ω, R2 = 68Ω
1.65V : R1 = 470Ω, R2 = 150Ω
1.66V : R1 = 390Ω, R2 = 120Ω
1.68V : R1 = 240Ω, R2 = 82Ω
1.71V : R1 = 330Ω, R2 = 120Ω
1.71V : R1 = 270Ω, R2 = 100Ω
1.72V : R1 = 220Ω, R2 = 82Ω
1.72V : R1 = 180Ω, R2 = 68Ω
1.73V : R1 = 470Ω, R2 = 180Ω
1.73V : R1 = 390Ω, R2 = 150Ω
1.76V : R1 = 390Ω, R2 = 150Ω
1.77V : R1 = 240Ω, R2 = 100Ω
1.81V : R1 = 270Ω, R2 = 120Ω
1.82V : R1 = 150Ω, R2 = 68Ω
1.82V : R1 = 330Ω, R2 = 150Ω
1.82V : R1 = 180Ω, R2 = 82Ω
1.83V : R1 = 390Ω, R2 = 180Ω
1.84V : R1 = 470Ω, R2 = 220Ω
1.86V : R1 = 390Ω, R2 = 180Ω
1.88V : R1 = 240Ω, R2 = 120Ω
1.89V : R1 = 470Ω, R2 = 240Ω
1.93V : R1 = 330Ω, R2 = 180Ω
1.93V : R1 = 150Ω, R2 = 82Ω
1.94V : R1 = 270Ω, R2 = 150Ω
1.96V : R1 = 390Ω, R2 = 220Ω
1.97V : R1 = 470Ω, R2 = 270Ω
1.99V : R1 = 390Ω, R2 = 220Ω
2.02V : R1 = 390Ω, R2 = 240Ω
2.03V : R1 = 240Ω, R2 = 150Ω
2.06V : R1 = 390Ω, R2 = 240Ω
2.08V : R1 = 330Ω, R2 = 220Ω
2.10V : R1 = 220Ω, R2 = 150Ω
2.12V : R1 = 390Ω, R2 = 270Ω
2.13V : R1 = 470Ω, R2 = 330Ω
2.16V : R1 = 330Ω, R2 = 240Ω
2.16V : R1 = 390Ω, R2 = 270Ω
2.19V : R1 = 240Ω, R2 = 180Ω
2.23V : R1 = 470Ω, R2 = 390Ω
2.25V : R1 = 150Ω, R2 = 120Ω
2.27V : R1 = 270Ω, R2 = 220Ω
2.27V : R1 = 330Ω, R2 = 270Ω
2.29V : R1 = 470Ω, R2 = 390Ω
2.29V : R1 = 180Ω, R2 = 150Ω
2.31V : R1 = 390Ω, R2 = 330Ω
2.36V : R1 = 270Ω, R2 = 240Ω
2.37V : R1 = 390Ω, R2 = 330Ω
2.40V : R1 = 240Ω, R2 = 220Ω
2.44V : R1 = 390Ω, R2 = 390Ω
2.50V : R1 = 470Ω, R2 = 470Ω
2.57V : R1 = 390Ω, R2 = 390Ω
2.61V : R1 = 220Ω, R2 = 240Ω
2.65V : R1 = 330Ω, R2 = 390Ω
2.66V : R1 = 240Ω, R2 = 270Ω
2.73V : R1 = 330Ω, R2 = 390Ω
2.74V : R1 = 470Ω, R2 = 560Ω
2.75V : R1 = 150Ω, R2 = 180Ω
2.76V : R1 = 390Ω, R2 = 470Ω
2.78V : R1 = 270Ω, R2 = 330Ω
2.78V : R1 = 220Ω, R2 = 270Ω
2.84V : R1 = 390Ω, R2 = 470Ω
2.92V : R1 = 180Ω, R2 = 240Ω
2.96V : R1 = 270Ω, R2 = 390Ω
2.97V : R1 = 240Ω, R2 = 330Ω
3.03V : R1 = 330Ω, R2 = 470Ω
3.05V : R1 = 390Ω, R2 = 560Ω
3.06V : R1 = 270Ω, R2 = 390Ω
3.06V : R1 = 470Ω, R2 = 680Ω
3.08V : R1 = 150Ω, R2 = 220Ω
3.13V : R1 = 220Ω, R2 = 330Ω
3.14V : R1 = 390Ω, R2 = 560Ω
3.18V : R1 = 240Ω, R2 = 390Ω
3.25V : R1 = 150Ω, R2 = 240Ω
3.28V : R1 = 240Ω, R2 = 390Ω
3.35V : R1 = 220Ω, R2 = 390Ω
3.37V : R1 = 330Ω, R2 = 560Ω
3.43V : R1 = 270Ω, R2 = 470Ω
3.43V : R1 = 390Ω, R2 = 680Ω
3.43V : R1 = 470Ω, R2 = 820Ω
3.47V : R1 = 220Ω, R2 = 390Ω
3.50V : R1 = 150Ω, R2 = 270Ω
3.54V : R1 = 180Ω, R2 = 330Ω
3.55V : R1 = 390Ω, R2 = 680Ω
3.70V : R1 = 240Ω, R2 = 470Ω
3.82V : R1 = 180Ω, R2 = 390Ω
3.83V : R1 = 330Ω, R2 = 680Ω
3.84V : R1 = 270Ω, R2 = 560Ω
3.88V : R1 = 390Ω, R2 = 820Ω
3.91V : R1 = 470Ω, R2 = 1K
3.92V : R1 = 220Ω, R2 = 470Ω
3.96V : R1 = 180Ω, R2 = 390Ω
4.00V : R1 = 150Ω, R2 = 330Ω
4.02V : R1 = 390Ω, R2 = 820Ω
4.17V : R1 = 240Ω, R2 = 560Ω
4.33V : R1 = 150Ω, R2 = 390Ω
4.36V : R1 = 330Ω, R2 = 820Ω
4.40V : R1 = 270Ω, R2 = 680Ω
4.43V : R1 = 220Ω, R2 = 560Ω
4.44V : R1 = 470Ω, R2 = 1.2K
4.46V : R1 = 390Ω, R2 = 1K
4.50V : R1 = 150Ω, R2 = 390Ω
4.51V : R1 = 180Ω, R2 = 470Ω
4.63V : R1 = 390Ω, R2 = 1K
4.79V : R1 = 240Ω, R2 = 680Ω
5.04V : R1 = 330Ω, R2 = 1K
5.05V : R1 = 270Ω, R2 = 820Ω
5.10V : R1 = 390Ω, R2 = 1.2K
5.11V : R1 = 220Ω, R2 = 680Ω
5.14V : R1 = 180Ω, R2 = 560Ω
5.17V : R1 = 150Ω, R2 = 470Ω
5.24V : R1 = 470Ω, R2 = 1.5K
5.30V : R1 = 390Ω, R2 = 1.2K
5.52V : R1 = 240Ω, R2 = 820Ω
5.80V : R1 = 330Ω, R2 = 1.2K
5.88V : R1 = 270Ω, R2 = 1K
5.91V : R1 = 220Ω, R2 = 820Ω
5.92V : R1 = 150Ω, R2 = 560Ω
5.97V : R1 = 180Ω, R2 = 680Ω
6.04V : R1 = 470Ω, R2 = 1.8K
6.06V : R1 = 390Ω, R2 = 1.5K
6.32V : R1 = 390Ω, R2 = 1.5K
6.46V : R1 = 240Ω, R2 = 1K
6.81V : R1 = 270Ω, R2 = 1.2K
6.92V : R1 = 150Ω, R2 = 680Ω
6.93V : R1 = 330Ω, R2 = 1.5K
6.94V : R1 = 180Ω, R2 = 820Ω
7.02V : R1 = 390Ω, R2 = 1.8K
7.10V : R1 = 470Ω, R2 = 2.2K
7.33V : R1 = 390Ω, R2 = 1.8K
7.50V : R1 = 240Ω, R2 = 1.2K
8.07V : R1 = 330Ω, R2 = 1.8K
8.08V : R1 = 150Ω, R2 = 820Ω
8.19V : R1 = 270Ω, R2 = 1.5K
8.30V : R1 = 390Ω, R2 = 2.2K
8.43V : R1 = 470Ω, R2 = 2.7K
8.68V : R1 = 390Ω, R2 = 2.2K
9.06V : R1 = 240Ω, R2 = 1.5K
9.58V : R1 = 330Ω, R2 = 2.2K
9.77V : R1 = 220Ω, R2 = 1.5K
9.90V : R1 = 390Ω, R2 = 2.7K
10.03V : R1 = 470Ω, R2 = 3.3K
10.37V : R1 = 390Ω, R2 = 2.7K
10.63V : R1 = 240Ω, R2 = 1.8K
11.25V : R1 = 150Ω, R2 = 1.2K
11.44V : R1 = 270Ω, R2 = 2.2K
11.48V : R1 = 330Ω, R2 = 2.7K
11.67V : R1 = 180Ω, R2 = 1.5K
11.83V : R1 = 390Ω, R2 = 3.3K
12.40V : R1 = 390Ω, R2 = 3.3K
12.71V : R1 = 240Ω, R2 = 2.2K
13.75V : R1 = 330Ω, R2 = 3.3K
15.31V : R1 = 240Ω, R2 = 2.7K
16.25V : R1 = 150Ω, R2 = 1.8K
16.53V : R1 = 270Ω, R2 = 3.3K
16.59V : R1 = 220Ω, R2 = 2.7K
18.44V : R1 = 240Ω, R2 = 3.3K
19.58V : R1 = 150Ω, R2 = 2.2K
20.00V : R1 = 220Ω, R2 = 3.3K
23.75V : R1 = 150Ω, R2 = 2.7K
24.17V : R1 = 180Ω, R2 = 3.3K
28.75V : R1 = 150Ω, R2 = 3.3K

For example, you need 4.5V from AA 1.5Vx3 in a series. But you do not have them. How to do? You have only LM317 and a lot of resistors. Yes, It can use it instead.

Look at the list above in 4.5V voltage we can use R1 = 150Ω, R2 = 390Ω.

It is easy, right?

LM317 heat sink calculator

What is the size of the heat sink enough?

While The LM317 is running. It is so hot. Though it has over-temperature cut-out. But we do not need it hot. We always install the heat sink.

Someone ask me. How much should you use the smallest heat sink? LM317 has a maximum temperature of 50 °C/W  without a heat sink.

I found this site good with the LM317 heat sink calculator.

The LM317 Heat sink, how big?

For example LM317 circuit

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worku

Thank’s & GBU this EC member .

vishal

sir i want 5v,2a power supply circuit with calculation from 230

sunday owen

pleasr can this idea be used to build solar charge controller?

Sumithra

Pls suggest any simple circuit which supplies output of +12V , -12V dual output with current rating of 1A
I/p supply is +24V DC .

CHRISTOPHER SILWAMBA

IAM LEANING A LOT I THANK VERY MUCH OUT OF THE MANY THINGS U ARE REVIEWING.

Abiodun Ogundipe

Dear Sir/Ma

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