LM317 Adjustable voltage regulator circuit Pinout and Working
LM317 Adjustable voltage regulator circuit Pinout and Working
In this article we will learn how to make LM317 Adjustable voltage regulator circuit Pinout and Working.
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What is LM-317?
The LM317 is a popular adjustable three-terminal positive voltage regulator integrated circuit (IC) manufactured by various semiconductor companies. It’s widely used in electronic circuits where a stable and adjustable voltage source is required.
Working Principle:
The LM317 regulates the output voltage based on a reference voltage between the ADJ pin and the output pin. By adjusting the resistance between the ADJ pin and ground, you can set the output voltage according to the desired value using the formula:
Vout=Vref×(1+R1R2)+Iadj×R2
Where:
- V out = Regulated output voltage
- V ref = Reference voltage (approximately 1.25V for LM317)
- R1 and R2= Resistors connected between the ADJ pin and output/input pins
- Iadj= Current flowing out of the ADJ pin (typically very small, around 50-100μA)
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LM317 Adjustable voltage regulator Pinout diagram:
Adjusting the Output Voltage:
To set the desired output voltage, you need to calculate the values of R1 and R2 using the formula above.
Alternatively, you can use a potentiometer to adjust the output voltage more dynamically.
Notes:
- Proper heat sinking might be necessary for higher current or voltage differences to avoid overheating.
- Input voltage should be higher than the desired output voltage by a reasonable margin for regulation to work correctly.
Remember to consult the LM317 datasheet and ensure you use appropriate capacitors and components for stability and protection in your circuit.
