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

5v fixed voltage regulator
LM340 is a regulated voltage (regulated voltage = 5V) transistor that maintains a stable supply of power to the electronic components. It is usually applied in embedded systems, Arduino installations, and digital electronics. The LM340 was easy to use and relatively small, and with built-in protection, makes it simple to regulate voltage in anything DIY.
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
| Pin | Function |
|---|---|
| Pin 1 | Input Voltage |
| Pin 2 | Ground |
| Pin 3 | Regulated 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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