Overview

The LM386 (and DIP-8 LM386N-1) is an iconic low-voltage audio power amplifier IC manufactured by Texas Instruments. Bundled in Elegoo, SunFounder, and generic Arduino starter kits (both as a bare 8-pin DIP chip and as a ready-to-use breakout module with a volume potentiometer), it drives small 4 Ω…32 Ω4\ \Omega \dots 32\ \Omega speakers in battery-powered audio devices, DIY radios, intercoms, and synthesizer projects.

Operating on a wide voltage supply range of 4.0V4.0\text{V} to 12.0V12.0\text{V} DC (up to 18V for LM386N-4), the LM386 features an internally set voltage gain of 20 (26 dB26\text{ dB}), which can be increased up to 200 (46 dB46\text{ dB}) by adding a single 10 μF10\ \mu\text{F} electrolytic capacitor between pins 1 and 8.

Quick reference

Operating voltage (VS)4.0 V to 12.0 V DC (LM386N-1) / up to 18.0 V DC (LM386N-4)
Output Power700 mW700\text{ mW} (0.7W0.7\text{W}) into 8 Ω8\ \Omega speaker at 9V9\text{V} supply
Quiescent Current4.0 mA4.0\text{ mA} typical (low battery drain)
Default Voltage Gain20 (26 dB26\text{ dB}, pins 1 & 8 left open)
Maximum Voltage Gain200 (46 dB46\text{ dB}, 10 μF10\ \mu\text{F} capacitor across pins 1 & 8)
Total Harmonic Distortion (THD)0.2%0.2\% typical at POUT=125 mW,f=1 kHzP_{OUT} = 125\text{ mW}, f = 1\text{ kHz}
Compatible Speakers4 Ω,8 Ω,16 Ω,32 Ω4\ \Omega, 8\ \Omega, 16\ \Omega, 32\ \Omega dynamic speakers

Pinout (DIP-8 Package)

text
             ┌───┴───┐
       GAIN ─┤ 1   8 ├─ GAIN
     -INPUT ─┤ 2   7 ├─ BYPASS
     +INPUT ─┤ 3   6 ├─ VS (+VCC)
        GND ─┤ 4   5 ├─ VOUT (Speaker)
             └───────┘
PinNameDescription
1GAINGain setting pin 1 (Connect 10 μF10\ \mu\text{F} cap to Pin 8 for 200x gain)
2 -INPUTInverting audio signal input
3 +INPUTNon-inverting audio signal input (Connect audio source via 10k potentiometer)
4GNDGround reference (0 V)
5VOUTAmplified AC audio output pin (Connect to speaker through 250 μF250\ \mu\text{F} cap)
6VSPositive DC supply power input (+4V to +12V DC)
7BYPASSDecoupling bypass pin (Connect 10 μF10\ \mu\text{F} cap to GND to prevent hum)
8GAINGain setting pin 2

Specifications

ParameterSymbolMinTypMaxUnitConditions
Supply Voltage (LM386N-1)VSV_S4.09.012.0VDC
Supply Current (Quiescent)ISI_S—4.08.0mAVS=6V,VIN=0V_S = 6\text{V}, V_{IN} = 0
Output Power (8 Ω,9V8\ \Omega, 9\text{V})POUTP_{OUT}500700—mWTHD = 10%
Default Voltage GainAVA_V152025V/VPins 1 & 8 open
Max Voltage GainAV_maxA_{V\_max}—200—V/V10 μF10\ \mu\text{F} cap across pins 1 & 8
Input ResistanceRINR_{IN}—50—kΩAudio input impedance

Basic Application Circuit (Gain = 20 vs Gain = 200)

text
        +9V Power Supply
           │
        [Pin 6: VS]
        LM386N
        [Pin 4: GND] ─── GND
           │
  Audio In ├─── [10k Potentiometer] ─── [Pin 3: +INPUT]
           │
        [Pin 5: VOUT] ─── [220µF Cap] ─── (+) [ 8Ω SPEAKER ] (-) ─── GND
  • Gain = 20 (Standard Audio Input): Leave Pin 1 and Pin 8 unconnected.
  • Gain = 200 (Weak Microphone Input): Connect the positive lead of a 10 μF10\ \mu\text{F} electrolytic capacitor to Pin 1 and negative lead to Pin 8.

Wiring (Breakout Module)

LM386 Module Pin→Arduino / Audio SourceNotes
VCC5V / 9V DCPower rail
GNDGNDSystem ground
INAudio Source / DAC PinConnect via 10k volume potentiometer
OUTSpeaker TerminalsConnect 8 ohm 0.5W speaker

Common mistakes

  • Forgetting the output DC blocking capacitor: Pin 5 (VOUT) sits at half supply voltage (VS/2V_S / 2). Connecting an 8 Ω8\ \Omega speaker directly to Pin 5 without a 220 μF…470 μF220\ \mu\text{F} \dots 470\ \mu\text{F} coupling capacitor burns out the speaker coil and overheats the IC.
  • Power supply noise hum: The LM386 is sensitive to ripple noise on the power rail. Connect a 10 μF10\ \mu\text{F} capacitor between Pin 7 (BYPASS) and GND to filter out power supply hum.

Notes

  • LM386 vs PAM8403 vs TDA2822: LM386 is a mono Class-AB amplifier (0.7W0.7\text{W}); PAM8403 is a stereo Class-D amplifier (3W+3W3\text{W}+3\text{W} at 90%90\% efficiency).

Assets & downloads