LM386N 3

LM386N-3 Low Voltage Audio Power Amplifier

Overview

The LM386N-3 is a versatile, low-voltage audio power amplifier designed for battery-operated and low-power consumer applications. This IC provides a cost-effective solution for amplifying audio signals with minimal external components. With its internally fixed gain of 20 (26 dB), the LM386N-3 simplifies circuit design while offering flexibility to increase gain up to 200 (46 dB) through external components.

This amplifier operates from a single power supply across a wide voltage range (4V-12V or 5V-18V for different versions), making it ideal for portable devices. The quiescent current drain is remarkably low (4 mA typical), ensuring efficient battery operation. The compact 8-pin DIP or SOP package allows for easy integration into various audio applications.

Key Features

• Battery operation capability (4-12V supply range for LM386N-3)
• Low quiescent current: 4 mA typical
• Internally fixed gain of 20 (26 dB)
• Adjustable gain up to 200 (46 dB) with external components
• Wide supply voltage range: 4V-12V (LM386N-3)
• Low distortion: 0.2% typical at 6V, 125 mW output
• Input referenced to ground for simplified design
• 8-pin DIP and SOP package options
• No output coupling capacitors required
• Minimum external components needed

Applications

The LM386N-3 is suitable for a wide range of low-power audio amplification applications including:

• Portable audio devices (AM/FM radios, MP3 players)
• Intercom systems
• TV sound systems
• Low-power public address systems
• Ultrasonic drivers
• Power converters
• Game consoles
• Battery-powered musical instruments
• Alarm systems
• Audio boosters for computer sound cards

Electrical Characteristics

(Unless otherwise specified, VCC = 6V, TA = 25°C, RL = 8Ω)

DC Characteristics

• Supply Voltage Range: 4V to 12V (LM386N-3)
• Quiescent Current: 4 mA typical, 8 mA maximum
• Output Power:
  • 325 mW typical at 6V, 8Ω, 10% THD
  • 700 mW typical at 9V, 8Ω, 10% THD
  • 1W typical at 16V, 8Ω, 10% THD (for LM386N-4)
• Voltage Gain: 26 dB typical (20x) internally, adjustable to 46 dB (200x)

AC Characteristics

• Bandwidth: 300 kHz typical
• Input Resistance: 50 kΩ typical
• Total Harmonic Distortion: 0.2% typical at 125 mW output
• Input Bias Current: 250 nA typical
• Power Supply Rejection Ratio: 50 dB typical

Package Information

The LM386N-3 is available in two standard package options:

8-Pin DIP (Dual In-line Package)

• Package Code: N
• Dimensions: 9.81 mm x 6.35 mm body
• Lead Pitch: 2.54 mm (0.1 inch)
• Lead Length: 3.3 mm typical
• Material: Molded plastic
• Operating Temperature Range: 0°C to +70°C

8-Pin SOP (Small Outline Package)

• Package Code: D
• Dimensions: 4.9 mm x 3.9 mm body
• Lead Pitch: 1.27 mm (0.05 inch)
• Lead Length: 0.6 mm typical
• Material: Molded plastic
• Operating Temperature Range: 0°C to +70°C

Pin Configuration and Functions

• Pin 1 (Gain): Gain setting pin. Connecting a capacitor between pins 1 and 8 bypasses the internal 1.35 kΩ resistor, increasing gain to 200.
• Pin 2 (Negative Input): Inverting input. Typically grounded in single-ended applications.
• Pin 3 (Positive Input): Non-inverting input. Audio signal input with DC bias at half supply voltage.
• Pin 4 (GND): Ground reference for the circuit.
• Pin 5 (Output): Amplifier output. Requires no DC blocking capacitor for most applications.
• Pin 6 (VCC): Positive power supply input (4-12V for LM386N-3).
• Pin 7 (Bypass): Bypass pin for power supply ripple rejection. A capacitor (typically 10 µF) to ground improves ripple rejection.
• Pin 8 (Gain): Gain setting pin. Used with Pin 1 to adjust amplifier gain.

Typical Application Circuit

A basic LM386N-3 application circuit includes:

• Power supply decoupling capacitor (100 µF) between VCC and GND
• Input coupling capacitor (0.1 µF) to block DC
• Gain setting components (10 µF capacitor and 1.2 kΩ resistor between pins 1 and 8 for maximum gain)
• Output filter network (0.05 µF capacitor and 10Ω resistor in series to ground)
• Bypass capacitor (10 µF) from pin 7 to ground

Design Considerations

When designing with the LM386N-3:

• Keep input leads short to minimize noise pickup
• Use proper grounding techniques - star grounding is recommended
• For battery operation, consider adding a large electrolytic capacitor (100-470 µF) near the IC to handle current surges
• Heatsinking may be required for continuous high-power operation
• For lowest noise, minimize the resistance between the bypass pin (7) and ground
• When driving lower impedance loads (4Ω), reduce supply voltage to prevent excessive power dissipation

Reliability and Quality

The LM386N-3 is manufactured with strict quality control measures:

• ESD protection on all pins
• 100% electrical testing
• High-temperature burn-in for reliability
• Moisture sensitivity level (MSL) rating of 1 (unlimited floor life)
• RoHS compliant versions available

Ordering Information

• LM386N-3/NOPB: 8-pin DIP, lead-free, tube packaging
• LM386N-3D/NOPB: 8-pin SOP, lead-free, tape and reel
• LM386N-3D: 8-pin SOP, standard, tape and reel