LM1875 Datasheet – 20W Audio Power Amplifier

What is LM1875?

This IC is a monolithic power amplifier offering very low distortion and high quality performance for consumer audio applications.

Part Number: LM1875

Function: 20W Audio Power Amplifier

Package: TO-220 Type

Manufacturer: National Semiconductor was acquired by Texas Instruments (TI) on September 23, 2011.


LM1875 audio power amplifier

Description :

The LM1875 design takes advantage of advanced circuit techniques and processing to achieve extremely low distortion levels even at high output power levels. Other outstanding
features include high gain, fast slew rate and a wide power bandwidth, large output voltage swing, high current capability, and a very wide supply range.

One of the key advantages of the LM1875 is its high output power capability, which makes it suitable for driving large speakers and for use in high-power audio systems. Additionally, its low distortion and wide bandwidth result in high-quality sound reproduction. However, the IC requires a higher supply voltage than some other audio amplifier ICs, which may limit its use in low-voltage applications.


1. Deliver up to 20 watts of output power per channel.

2. Simple circuit design that requires only a few external components.

3. Built-in thermal shutdown feature to prevent damage to the IC and connected components.

4. Suitable for high-fidelity audio applications, stereo amplifiers, home theater systems, and active speakers.

5. Built-in thermal shutdown feature that helps to prevent damage to the IC and the connected components.

6. Low distortion, high slew rate, and wide bandwidth, resulting in high-quality sound reproduction.


LM1875 pinout datasheet


1. Up to 30 watts output power
2. AVO typically 90 dB
3. Low distortion: 0.015%, 1 kHz, 20 W
4. Wide power bandwidth: 70 kHz
5. Protection for AC and DC short circuits to ground
6. Thermal protection with parole circuit
7. High current capability: 4A
8. Wide supply range 16V-60V
9. Internal output protection diodes
10. 94 dB ripple rejection


1. High performance audio systems
2. Bridge amplifiers
3. Stereo phonographs
4. Servo amplifiers
5. Instrument systems



1. What is the difference with LM3875?

The LM3875 is a higher-power version of LM1875, capable of delivering up to 56 watts of output power per channel. LM3875 also has a wider supply voltage range of 20V to 84V DC.

LM1875 Datasheet

LM1875 pdf


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BC547 Datasheet – 0.1A, 45V, NPN Amplifier – Fairchild

What is BC547?

This is a general-purpose NPN bipolar junction transistor (BJT) commonly used in electronic circuits. It is designed for low-power applications and has a voltage rating of 45V and a maximum current rating of 100mA. The BC547 is housed in a small TO-92 package and is widely used in applications such as signal amplification, switching, and oscillator circuits.

Function : NPN General Purpose Amplifier

Package : TO 92 type

Manufacturer: Fairchild Semiconductor Corporation, a semiconductor manufacturing company, was acquired by ON Semiconductor Corporation on September 18, 2016.


BC547 pinout image

The BC547 is a general-purpose NPN BJT with a voltage rating of 45V and a maximum current rating of 100mA. It has a low collector-emitter saturation voltage, which reduces power loss and improves efficiency.  This device is designed for use as general purpose amplifiers and switches requiring collector currents to 300 mA. Sourced from Process 10. See PN100A for characteristics.

BC547 Datasheet


1. Switching and Amplifier

2. Collector-Base Voltage : Vcbo = 50V

3. Collector-Emitter Voltage : Vceo =45V

4. Emitter-Base Voltage: Vebo = 6V

5. Collector Current (DC) : Ic = 100mA


1. The BC547 is designed for low-power applications and may not be suitable for high-power circuits.

2. Its maximum current rating of 100mA may be too low for some applications.

3. It has a relatively low maximum voltage rating of 45V, which may limit its use in some circuits.

BC547 Datasheet

BC547 pdf



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