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Last updated: August 4, 2025

5V Voltage Regulator Circuit using LM340 IC

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Components List

Single phase Light

LM340 Voltage Regulator

Fixed positive voltage regulator (commonly 5V, 12V, 15V)

Single Phase DP ELCB

0.47µF Capacitor

Medium-value film or ceramic capacitor for AC/DC circuits

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5V Voltage Regulator

Build a stable 5V DC power supply using the LM340 voltage regulator. Ideal for microcontroller circuits and small electronics projects.

negative voltage converter

To assure a stable 12V output, the 12V Negative Voltage Regulator circuit is important to the analog and audio electronics. It also protects devices against variations in voltage and provides stable operations. This tutorial and design guide you through how to design, compute, and test a very simple 12V regulator circuit utilizing elements such as the LM7912, capacitors, and an appropriate transformer or DC power supply.

LM340 Voltage Output Formula:

Vout = 5V (Fixed for LM340-5.0)

Recommended Capacitor Values:

  • Input Capacitor: 0.33µF
  • Output Capacitor: 0.1µF

lm340 voltage regulator circuit

The LM340 family is a very common voltage regulator that still sells as it offers a stable 5 volts output, making it suitable to drive microcontrollers, sensors, and digital circuits. It has numerous current ratings (LM340-5.0, LM340T-5, etc.), and it features thermal shutdown and short-circuit protection. The device helps in making circuits easy to design because it negates the use of a complicated regulation system. The LM340 is perfect for beginners and professional electronic designs with a good supply of power, with very few external capacitors.

5v voltage regulator lm340

PinFunction
Pin 1Input Voltage
Pin 2Ground
Pin 3Regulated 5V Output

Frequently Asked Questions - 5V Voltage Regulator:

What is LM340 voltage regulator?

A fixed 5V linear voltage regulator IC used for stable power supply.

How to wire LM340 for 5V output?

Connect Vin to input, GND to ground, and Vout gives regulated 5V.

What capacitors are needed with LM340?

Use 0.33µF at input and 0.1µF at output for stability.

Can LM340 be used for Arduino?

Yes, it provides a clean 5V output suitable for Arduino boards.

Is LM340 same as 7805?

Yes, functionally they are similar 5V regulators with slight variations.

What is max input voltage for LM340?

Typically up to 35V, but check datasheet for your variant.

Does LM340 need a heatsink?

Yes, when current exceeds 500mA or under high input voltage.

What is the output current of LM340?

Varies by model, commonly 1A or 1.5A.

Is LM340 suitable for battery circuits?

Yes, for regulated 5V output from higher voltage sources.

What is the dropout voltage of LM340?

Typically around 2V, so input should be at least 7V.

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Md. Jony Islam is a highly skilled professional with expertise in electronics, electrical, mechanical, and civil engineering, as well as finance. Specializing intransformer service and maintenance for 33/11kV substations, he ensures reliable and efficient electrical systems. His mechanical engineering skills drive innovative designs, while his financial acumen supports effective project budgeting. With a strong foundation in civil engineering, he contributes to robust infrastructure development. Md. Jony Islam's multidisciplinary approach ensures efficiency, quality, and reliability across all projects.