Phone amplifier using lm380 IC
Amplifier Projects Electronics tutorial OP-AMP tutorial

LM380 Audio Power Amplifier Circuit And it’s Working

The LM380 is an audio power amplifier for consumer application. Its internal gain is fixed to 14dB in order to keep the system cost minimum. A unique input stage allows inputs to be referenced with the ground. The output gets automatically self-centered to one half the supply voltage.

The output amplifier is short circuit proof with an internal thermal limiting system. The packaging is standard dual-in-line. Also, a copper lead frame is used with the center three pins on either side comprising a heat sink. This makes the device easy to use in a standard PCB layout.

Features of LM 380 Audio power amplifier IC:

  • It has a wide Supply Voltage Ranging from 8V-22V
  • Voltage Gain is Fixed at 50
  • Max watts output power is 5W
  • Low Quiescent Power Drain: 0.13W (At voltage supply is 18V)
  • It has a high Peak Current Capability of 1.3A.

Watch this video to understand better.

LM380 IC Pinout diagram:

IC LM380 Pinout

LM380 IC is available in a 14 pin and 8 pin DIP package. In 14 pin ic, the pin labels are as follows.

1 Bypass, 2 Non-inverting input terminal, 3,4,5,7,10,11 and 12 are the ground pins, pin 8 is an output pin, 14 is the supply, pin 9 and 13 are not connected. The ground pins act as a heatsink.

LM380 opamp diagram

Pin description of 8 pin LM380 IC:

LM380 Pinout diagram

In this 8 pin IC, all the ground pins are made common. Also, the not connected pins are reduced to one. Here all the pins are utilized, and IC is very compact.

The first pin is not connected, pin 2 is non-inverting terminal, pin 3 is inverting input terminal, pin 4,5 is ground, 6 is output, 7 is supply pin and pin 8 is bypass pin.

LM380 Audio Power Amplifier Circuit

Phono Amplifier using LM380 IC:

This circuit can give an output power of about 3 to 5 watts. It is simple to construct. It can drive 4Ω to 8Ω speakers with a good base.

LM380 Audio Power Amplifier Circuit

Bridge Amplifier using LM380 IC:

You can construct a bridge amplifier circuit using two LM380 Audio Power Amplifier ICs. Here the speaker is not connected to the ground. The two input terminals of the speaker are connected to the output of the LM380 IC.

Bridge amplifier using LM380 IC

Phase Shift Oscillator Circuit by LM380:

Phase Shift Oscillator using LM380 IC

A phase shift oscillator circuit is as shown in the figure. This circuit can produce a Sine wave of a desired low to medium frequency. LM380 is used to produce a phase shift of 180° in the circuit. An RC network of three resistors and capacitors is connected in the feedback path. Each RC element produces a phase shift of my 60°. And together they make a complete 180° phase shift. This is how the phase shift oscillator circuit works.

Applications of LM380 Audio Power Amplifier IC:

It is widely used in simple phonograph amplifiers, intercoms.

Used in line drivers, teaching machine outputs, alarms, ultrasonic drivers,

It is also used in TV sound systems, AM-FM radio, small servo drivers, and power converters.

Thank you for reading, comment down your queries.


2 Replies to “LM380 Audio Power Amplifier Circuit And it’s Working

  1. This was my very first amoplifier I built in my teens decades ago. It was a brilliant sound and temptered to try it again, not tried the bridge configeration

  2. My first amp but used a 1M pot across two inputs and only 1 x 470uf to speaker. It sounded brilliant. Nver seen bridged one before must try it. I have two modules LM386 200 times gain, chip far to small for a heatsink

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