LM317 three-terminal adjustable voltage regulator module

# Introduction

LM317 is one of the most widely used power integrated circuits. It not only has the simplest form of a fixed three-terminal voltage regulator circuit, but also has the characteristics of adjustable output voltage. In addition, it also has the advantages of wide voltage regulation range, good voltage regulation performance, low noise, and high ripple suppression ratio. LM317 is an adjustable 3-terminal positive voltage regulator. It can provide more than 1.5A of current when the output voltage range is 1.2V to 37V. This regulator is very easy to use.

![1.png] **Main parameters**
Output voltage: 1.25-37V DC;
Output current: 5mA-1.5A;
The chip has overheating, overcurrent, and short-circuit protection circuits;
Maximum input-output voltage difference: 40V DC,
minimum input-output voltage difference: 3V DC;
Operating environment temperature: -10-+85℃.
Storage environment temperature: -65-+150℃.

The output voltage of the voltage regulator can be calculated by the following formula, Vo=1.25(1+R2/R1). Just from the formula itself, the resistance values ​​of R1 and R2 can be set arbitrarily. However, as a formula for calculating the output voltage of a voltage-stabilized power supply, the resistance values ​​of R1 and R2 cannot be set arbitrarily. First of all, the output voltage range of the 317 voltage regulator is Vo=1.25V-37V (the output voltage range of high-output-voltage 317 voltage regulators such as LM317HVA, LM317HVK, etc. is Vo=1.25V-45V), so the ratio range of R2/R1 can only be 0-28.6.
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# Physical display

![1.jpg] ![1 (2).jpg] ![1 (3).jpg]
## Input 12V voltage:

![1 (4).jpg]



## Output voltage:

![1 (5).jpg]