How to Use LM386: Examples, Pinouts, and Specs

The LM386 is a popular low voltage audio power amplifier integrated circuit (IC) designed for battery-operated devices. It is capable of delivering up to 1 watt of power to a speaker, making it an ideal choice for portable audio devices, intercom systems, and small audio amplifiers. Its simplicity and ease of use have made it a favorite among hobbyists and professionals alike.

• Supply Voltage (Vcc): 4V to 12V
• Output Power: Up to 1W (8Ω load, 6V supply)
• Gain: Adjustable from 20 to 200
• Input Impedance: 50kΩ (typical)
• Quiescent Current: 4mA (typical at 6V)
• Total Harmonic Distortion (THD): 0.2% (AV = 20, VS = 6V, RL = 8Ω, PO = 125mW)
• Signal to Noise Ratio: 90dB (typical)

1. Power Supply: Connect the positive terminal of your power source to pin 3 (Vs) and the ground to pins 1 and 8.
2. Input Signal: Connect your audio input to pin 2 (IN+). If necessary, use a coupling capacitor to block DC offsets.
3. Output: Connect pin 4 (OUT) to the speaker, with an optional capacitor in series to block DC.
4. Gain Control: To set the gain, connect a resistor and capacitor between pins 1 and 8. Without external components, the gain defaults to 20.
5. Bypass Capacitor: A capacitor can be connected to pin 6 (Bypass) to reduce noise.
6. Zobel Network: Connect a resistor and capacitor network from pin 5 to ground to stabilize the output against high-frequency oscillations.

• Use a decoupling capacitor (typically 0.1µF) close to the power supply pins to filter out noise.
• Keep the input signal lines as short as possible to minimize interference.
• Ensure that the power supply voltage does not exceed the maximum rating of 12V.
• Use a heat sink if operating near the maximum output power to prevent overheating.

// Example code to drive an LM386 amplifier with an Arduino UNO

int speakerPin = 9; // Connect to the input of the LM386

void setup() {
  pinMode(speakerPin, OUTPUT);
}

void loop() {
  // Generate a 1kHz tone for 1 second
  tone(speakerPin, 1000, 1000);
  delay(1500); // Wait for 1.5 seconds
}

• Low Volume: Check the gain setting and ensure the power supply is adequate.
• Distortion: Ensure the input signal level is not too high, causing clipping.
• No Sound: Verify connections, check the speaker, and ensure the IC is not damaged.

• No Output: Check for proper supply voltage and ground connections.
• Hum or Noise: Use a bypass capacitor on the power supply and keep input leads short.
• Overheating: Make sure the power dissipation is within limits; use a heat sink if necessary.

Q: Can I use the LM386 with a 3.3V supply? A: The LM386 is designed for a minimum of 4V. Operation below this may result in reduced performance or no function.

Q: How can I increase the gain? A: Connect a 10µF capacitor between pins 1 and 8 to increase the gain to 200.

Q: Is the LM386 mono or stereo? A: The LM386 is a mono amplifier. For stereo applications, use two LM386 ICs.

Remember to always consult the LM386 datasheet for the most accurate and detailed information.