LM386 Low-Voltage Audio Power Amplifier
The LM386 is a low-voltage audio power amplifier. It differs from an op-amp because it is intended to deliver useful power to a low-impedance load such as a small loudspeaker rather than merely process a small signal.
small audio signal→LM386
AUDIO POWER AMP→small speaker
AUDIO POWER AMP→small speaker
Designed for few external parts
The LM386 became popular in battery-powered radios, intercoms, signal tracers, alarms, hobby amplifiers, and other small audio projects because it can operate from a low-voltage supply with relatively few external components.
Gain
The familiar LM386 configuration has an internal voltage gain of about 20. Components connected between its gain-control pins can raise the gain, with classic configurations covering gains from about 20 to 200.
Power amplifier rather than op-amp
| Op-amp | LM386-style audio power amplifier |
|---|---|
| Usually used with external feedback to establish precise signal gain and function. | Designed specifically to deliver more current and power into an audio load. |
| Often drives another amplifier stage or high-impedance load. | Can directly drive a small speaker in suitable circuits. |
| Output-current capability depends heavily on the op-amp family. | Output stage is designed around the needs of low-power audio. |
Speaker power, supply voltage, load impedance, distortion, package heating, bypassing, and output-coupling requirements all matter. Follow the datasheet example circuits rather than treating the IC as an ideal amplifier block.
Manufacturer reference: TI LM386.