LM1875 Audio Amplifier

LM1875 Audio Amplifier
LM1875 Audio Amplifier
LM1875 Audio Amplifier Pinout
LM1875 Audio Amplifier
LM1875 Audio Amplifier Pinout

click on image to enlarge

The LM1875 is a Class-AB Audio Amplifier from Texas Instruments. It can deliver an output power of 20W into a 4Ω or 8Ω speaker with a maximum current of 4A. The IC can operate in single rail or dual rail power supply and is commonly used in high power audio amplifier designs.


Pin Configuration 

Pin Number

Pin Name



Non – Inverting Input

Non inverting end (+) of Amplifier


Inverting Input

Inverting end (-) of Amplifier



Negative supply voltage or ground



This pin outputs the amplified signal



Positive supply voltage



  • Low frequency class AB amplifier most suited for audio amplification
  • Operating Voltage: 16V to 60V
  • Output: 20Watts with 4Ω/8 Ω speaker
  • Output Current: 4A
  • Open Loop Gain Gain: 90dB
  • Bandwidth: 70KHz
  • Short circuit and thermal protection is available
  • Breadboard friendly
  • Available in 5-pin TO220 package

Note: Complete Technical Details can be found at the LM1875 datasheet given at the end of this page.


Alternative to LM1875: TDA2050

Other Audio Amplifiers: LM386, TDA1554, TDA2030, TDA7294, TDA7265, TDA7279, TDA2005,


Introduction to LM1875

The LM1875 is a 20W Class AB audio amplifier with a wide operating voltage and high bandwidth. The IC can driver 20W speakers with a maximum current of 4A and can also go to a maximum of 30W.  It can operate in both with single rail and dual rail power supply, and has some in-built protection features making it robust.

The LM1875 is breadboard friendly and hence can be easily tested using a breadboard. A sample application circuit for LM1875 is given below. The datasheet given at the bottom of this page consists of more details on this design.

Circuit using TDA2050 32W Audio Power Amplifier


LM1875 is a 5-pin Amplifier IC. The pin 5 and 3 are used to power the Amplifier IC, and the audio signal to be amplified is given in through pin 1 which is the non-inverting input. The amplified audio output can be obtained through pin 4. The values of the components given above are the values recommended by manufactures.



  • Used for Audio signal Amplification
  • Suitable for high power amplification
  • Capable of operating on dual/split power supply
  • Can be used to cascade audio speakers


2-D Model (PDIP)

TDA2050 32W Audio Power Amplifier 2D-Model

TDA2050 32W Audio Power Amplifier Dimension

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