Op-Amps & ComparatorsActive

LM386N-1

Manufacturer: Texas Instruments

Figures from the datasheet: Texas Instruments SNAS545D, rev. D, August 2023

Low-voltage mono audio power amplifier with an internal gain of 20, adjustable to 200, that drives a 4–32 Ω speaker from a 4–12 V supply with a handful of external parts.

PackagesPDIP-8, SOIC-8, VSSOP-8

Supply voltage4 – 12 V

Temperature range0 – 70 °C

Official Datasheet (PDF)

Technical Overview

The LM386 is a mono power amplifier for low-voltage consumer audio. Its gain is set internally to 20 (26 dB) to keep the external part count low; a capacitor between pins 1 and 8 bypasses the internal 1.35 kΩ resistor and raises the gain to 200 (46 dB), and a resistor in series with that capacitor sets any gain in between. Both inputs are referenced to ground through internal 50 kΩ resistors, and the output biases itself to half the supply voltage, so a speaker is connected through a series capacitor. Quiescent current is 4 mA typical at 6 V, which makes the part suited to battery operation. The figures on this page come from the Texas Instruments LM386 datasheet (SNAS545D); TI notes that its application circuits are not part of the component specification and must be validated in the final design.

Package Pinout & Alternate Functions

Interactive package pinout and pin mapping for PDIP-8.

Package illustration, not a dimensioned mechanical drawing.

8 / 8 pins

Pin name	Type	5V Tolerant	Alternate functions / details
GAIN	passive	—	Gain setting pin. Open together with pin 8, the internal 1.35 kΩ resistor sets the gain to 20 (26 dB); a capacitor from pin 1 to pin 8 raises it to 200 (46 dB), and a resistor in series with that capacitor sets any gain between 20 and 200.
-INPUT	analog in	No	Inverting input, biased to ground through an internal 50 kΩ resistor. Input voltage −0.4 V to +0.4 V (absolute maximum); tie to ground when the signal drives pin 3.
+INPUT	analog in	No	Noninverting input, biased to ground through an internal 50 kΩ resistor. Input voltage −0.4 V to +0.4 V (absolute maximum).
GND	ground	—	Ground reference.
VOUT	analog out	—	Amplifier output; it biases itself to about half the supply voltage, so the speaker is AC-coupled through a series capacitor (250 µF in the datasheet circuits).
VS	power in	—	Supply voltage: 4 V to 12 V recommended (LM386N-4: 5 V to 18 V). TI recommends a capacitor to GND close to this pin.
BYPASS	analog out	—	Bypass decoupling path (datasheet pin type O). May be left open; the datasheet specifies PSRR with a 10 µF capacitor on this pin.
GAIN	passive	—	Gain setting pin, used together with pin 1 (see pin 1).

Key Specifications

Parametric attributes

Parameter	Min	Typical	Max	Unit	Test condition
Operating Supply Voltage(VS)	4	4–12	12	V	LM386N-1, -3, LM386M-1, LM386MM-1; LM386N-4: 5 V to 18 V
Quiescent Current(IQ)	—	4	8	mA	VS = 6 V, VIN = 0
Output Power(POUT)	250	325	—	mW	LM386N-1, LM386M-1, LM386MM-1: VS = 6 V, RL = 8 Ω, THD = 10%
Output Power (LM386N-3)(POUT)	500	700	—	mW	VS = 9 V, RL = 8 Ω, THD = 10%
Voltage Gain(AV)	—	26	—	dB	VS = 6 V, f = 1 kHz, pins 1 and 8 open (gain 20); 46 dB with 10 µF from pin 1 to pin 8
Bandwidth(BW)	—	300	—	kHz	VS = 6 V, pins 1 and 8 open
Total Harmonic Distortion(THD)	—	0.2	—	%	VS = 6 V, RL = 8 Ω, POUT = 125 mW, f = 1 kHz, pins 1 and 8 open
Power Supply Rejection Ratio(PSRR)	—	50	—	dB	VS = 6 V, f = 1 kHz, CBYPASS = 10 µF, pins 1 and 8 open, referred to output
Input Resistance(RIN)	—	50	—	kΩ	—
Input Bias Current(IBIAS)	—	250	—	nA	VS = 6 V, pins 2 and 3 open
Speaker Impedance(RL)	4	4–32	—	Ω	Recommended operating minimum 4 Ω; application examples use 4 Ω to 32 Ω

Absolute Maximum Ratings

Max supply voltage (VDD/VCC)	15 V
Max input voltage	0.4 V
Storage temperature	-65 – 150 °C
ESD rating (HBM)	1000 V
Thermal resistance θJA (PDIP-8)	53.4 °C/W
Thermal resistance θJC (PDIP-8)	42.1 °C/W
Thermal resistance θJA (SOIC-8)	115.7 °C/W
Thermal resistance θJC (SOIC-8)	59.7 °C/W
Thermal resistance θJA (VSSOP-8)	169.3 °C/W
Thermal resistance θJC (VSSOP-8)	73.1 °C/W

Hardware Engineering Gotchas

Real-world hardware caveats, PCB layout constraints and silicon errata to know before manufacturing.

Critical

Input Range Is Only ±0.4 V

The inputs are referenced to ground and their absolute maximum input voltage is −0.4 V to +0.4 V. A line-level or headphone signal can exceed this. At a gain of 20 on a low supply, the output clips well before the input reaches that limit.

Mitigation

Feed the signal through a volume potentiometer to pin 3, as in the datasheet circuits (10 kΩ from the input to ground, wiper to pin 3), and keep pin 3 within ±0.4 V.

Warning

No Supply Decoupling at Pin 6

TI recommends a capacitor to GND close to the supply pin and specifies power supply rejection with a 10 µF bypass capacitor on pin 7. Without decoupling, supply ripple and long battery leads reach the output.

Mitigation

Place a capacitor from pin 6 to GND next to the IC (the datasheet gives no value) and keep the speaker leads short; add a capacitor on pin 7 when supply noise is audible.

Warning

Unused Input at High Gain

With pins 1 and 8 bypassed for a gain of 200, an unbypassed unused input degrades the gain and can make the amplifier unstable.

Mitigation

Bypass the unused input with 0.1 µF, or short it to ground, depending on the DC source resistance on the driven input (TI §9.2.1.2.2).

Note

Closed-Loop Gain Below 9 Is Unstable

The amplifier is compensated only for closed-loop gains greater than 9, which limits how much the feedback can be loaded when shaping the frequency response.

Mitigation

For bass boost with a series RC from pin 1 to pin 5, keep R at 10 kΩ or more when pin 8 is open; with pins 1 and 8 bypassed R can go down to 2 kΩ (TI §9.2.1.2.1).

Cross-Reference & Equivalents

Part number (MPN)	Manufacturer	Compatibility	Electrical differences / BOM considerations
LM386N-3	Texas Instruments	differing electrical limits	Same pinout and PDIP-8 package; output power is specified at VS = 9 V, RL = 8 Ω (700 mW typical, 500 mW minimum).
LM386N-4	Texas Instruments	differing electrical limits	Same pinout and PDIP-8 package; 5 V to 18 V supply (22 V absolute maximum) and output power specified at VS = 16 V, RL = 32 Ω (1000 mW typical).

Reference Circuits

Audio amplifier with gain 20

Topology: Fixed-gain speaker amplifier with volume control and output coupling capacitor.

Inspect schematic Open in Web CAD Editor

LM386 Audio Amplifier with Bass Boost

Topology: Frequency-shaped feedback using a series 10 kΩ and 33 nF branch between pins 1 and 5.

Inspect schematic Open in Web CAD Editor

Official Documentation & Cited Datasheets

Primary semiconductor vendor datasheets, errata, and application notes.

DATASHEETTexas Instruments

LM386 Low Voltage Audio Power Amplifier

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Technical Overview

Package Pinout & Alternate Functions

Key Specifications

Parametric attributes

Absolute Maximum Ratings

Hardware Engineering Gotchas

Cross-Reference & Equivalents

Reference Circuits

Audio amplifier with gain 20

LM386 Audio Amplifier with Bass Boost

Official Documentation & Cited Datasheets

LM386 Low Voltage Audio Power Amplifier

Help keep this page accurate

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