The LM1870N is a monolithic power amplifier capable of delivering 20W into a 4Ω or 8Ω load. It was originally manufactured by National Semiconductor, which is now part of Texas Instruments (TI). This amplifier is designed with a minimum of external components, making it simple to use and implement in audio amplifier applications.

Applications

• Audio Amplifiers: Used in stereo systems, home theater systems, and portable audio devices.
• Musical Instrument Amplifiers: Can be used in guitar amplifiers and keyboard amplifiers.
• Automotive Amplifiers: Used in car audio systems.
• Public Address Systems: Used in PA systems for amplifying speech and music.
• Small Powered Speakers: Integrated in powered computer speakers and other small audio devices.

Features

• High Output Power: Delivers up to 20W into a 4Ω or 8Ω load.
• Wide Supply Voltage Range: Operates from ±10V to ±22V.
• Low Distortion: Provides clean and clear audio amplification.
• Short Circuit Protection: Protects the amplifier from damage due to short circuits.
• Thermal Overload Protection: Prevents the amplifier from overheating.
• Internal Current Limiting: Limits the output current to protect the amplifier and the load.

Benefits

• Simple to Use: Requires a minimum of external components.
• High Performance: Delivers high-quality audio amplification.
• Reliable Operation: Protected against short circuits and thermal overload.
• Cost-Effective Solution: Provides a cost-effective solution for audio amplification.

Additional Details

The LM1870N typically comes in a 9-pin TO-220 package. It is a Class AB amplifier, which provides a good balance of efficiency and linearity. The amplifier requires a heatsink to dissipate heat when operating at high power levels. The input impedance is relatively high, making it easy to interface with various audio sources. Texas Instruments continues to manufacture the LM1870N or suitable replacements, ensuring its continued availability for audio amplifier applications. Key specifications include a THD+N (Total Harmonic Distortion + Noise) figure suitable for quality audio reproduction. The internal protection circuitry is crucial for safeguarding the amplifier under fault conditions.