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DIP-8 · LM386
ActiveLow-Voltage Audio Power Amplifier
LM386
Texas Instruments · DIP-8 · Low-Voltage Audio Power Amplifier
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Overview
The LM386 is TI's low-voltage audio power amplifier, designed to run directly from the batteries that power portable consumer electronics. Supply range is 4 V to 12 V for the LM386N-1, LM386N-3, LM386M-1 and LM386MM-1 variants, and 5 V to 18 V for the LM386N-4, with absolute maximum ratings of 15 V and 22 V respectively. Quiescent current is only 4 mA typical — about 24 mW from a 6 V supply — and the output self-centres at half the supply voltage, so a single-ended speaker can be driven through one coupling capacitor with no split rail and no output inductor.
The internal feedback network of two 15 kΩ resistors and a 1.35 kΩ emitter resistor fixes the voltage gain at 20 (26 dB). Placing a 10 µF capacitor between pins 1 and 8 bypasses the 1.35 kΩ resistor and raises the gain to 200 (46 dB); adding a resistor in series with that capacitor sets any intermediate value, and a capacitively coupled resistor or FET from pin 1 to ground gives voltage-controlled gain. Output power is 325 mW typical into 8 Ω from 6 V at 10 % THD, rising to 700 mW typical from 9 V and 1 W typical into 32 Ω from 16 V on the LM386N-4. Bandwidth is 300 kHz, total harmonic distortion is 0.2 % typical at 125 mW into 8 Ω from 6 V, power supply rejection is 50 dB with a 10 µF bypass capacitor on pin 7, input resistance is 50 kΩ and input bias current is 250 nA.
Good layout practice matters more with this part than with most. Use a 10 Ω resistor in series with a 0.05 µF capacitor from the output to ground (a Zobel network) to keep the amplifier stable into inductive speaker leads, keep the ground return of the input stage separate from the speaker return, bypass the supply within a few millimetres of pin 6, and do not exceed a gain of 200 or the internal biasing degrades. TI publishes reference layouts for gain-20, gain-200 and split-supply configurations.
The LM386 remains one of the highest-volume audio parts in the world, with SOIC-8, VSSOP-8 and PDIP-8 options and numerous Asian second sources that are pin and function compatible. MOQ is 1 reel (2,500 pcs for SOIC-8) or 100 pcs loose; Shenzhen stock ships in 1-2 days. Counterfeits show up as parts with high noise floor, gain far below 200 when bypassed, or output stages that clip early — sample-test distortion and quiescent current before releasing a lot.
Key Features
- Operates from a 4 V to 12 V single supply (5 V to 18 V on LM386N-4)
- Gain internally set to 20, extendable to 200 with one 10 µF capacitor
- Only 4 mA quiescent current — ideal for battery products
- Up to 700 mW typical into 8 Ω from a 9 V rail at 10 % THD
- Ground-referenced inputs with self-centring output stage
Typical Applications
- Portable radios, intercoms, toys and voice prompt modules
- Small speakers, buzzers and piezo transducer drivers
- Line drivers and headphone amplifiers in low-voltage gear
- Ultrasonic drivers and small servo amplifier stages
- Educational kits, Arduino audio shields and DIY guitar amps
Specifications
- Supply Voltage
- 4 to 12 V
- Voltage Gain
- 20 to 200 V/V
- Output Power (Typ, VS = 9 V, RL = 8 Ω)
- 700 mW
- Quiescent Current (VS = 6 V)
- 4 mA
- Bandwidth
- 300 kHz
- Total Harmonic Distortion (Typ)
- 0.2 %
- Input Resistance
- 50 kΩ
- Operating Temperature
- 0 to 70 °C
- Pins
- 8
- RoHS
- Compliant
Procurement Tips
For battery products, specify the LM386M-1 SOIC-8 rather than the DIP-8 — same die, lower profile and cheaper per unit at volume — and keep the DIP only for repair spares and kit businesses.
Frequently Asked Questions
How do I set the LM386 gain to 20, 50 or 200?
With pins 1 and 8 open the internal 1.35 kΩ resistor sets gain 20. A 10 µF capacitor directly from pin 1 to pin 8 bypasses that resistor for gain 200. Adding a series resistor with the capacitor gives intermediate values — about 1.35 kΩ yields gain 50 — and capacitively coupling a resistor from pin 1 to ground allows external or voltage-controlled gain.
What is the difference between LM386N-1, LM386N-3 and LM386N-4?
All are DIP-8 parts with identical pinouts. The N-1 and N-3 are rated for 4 V to 12 V operation, while the N-4 is specified from 5 V to 18 V with a 22 V absolute maximum and delivers up to 1 W typical into 32 Ω from 16 V. Choose the N-4 when running from a 12 V rail where transients can push past 12 V.
Why is my LM386 circuit oscillating or howling?
Three usual causes: the output trace runs near the input (route them apart and star the grounds), the Zobel network is missing (fit 10 Ω in series with 0.05 µF from pin 5 to ground), or the supply bypass is too far from pin 6. Excessive gain with an open input also turns the amplifier into a microphone — always terminate pin 3 through a resistor.
Can the LM386 drive an 8 Ω speaker at usable volume from 5 V?
Yes, but expect only a few hundred milliwatts. From a 5 V rail the output can swing roughly ±2 V into 8 Ω, which is about 250 mW to 300 mW — enough for a small speaker in a handheld device. For 1 W or more, move to a 9 V supply or choose a class D part such as the PAM8403.
What is the purpose of the bypass pin 7?
Pin 7 biases the internal voltage divider that sets the output quiescent point. Connecting 10 µF from pin 7 to ground raises power supply rejection to about 50 dB and reduces turn-on thump. Leave the capacitor polarised correctly and do not short pin 7 to the supply.
How do I verify a lot of LM386 is genuine?
Bench-test five samples for quiescent current (should read close to 4 mA at 6 V), gain with pins 1-8 bypassed (should approach 200, or 46 dB), THD at 125 mW into 8 Ω (0.2 % typical) and noise floor. Counterfeit parts usually show one or two of these out of specification. Genuine TI parts have laser marking and consistent package weight.
What is the MOQ and lead time?
MOQ 1 reel (2,500 pcs SOIC-8) or 100 pcs loose for the DIP-8 prototyping quantity. Shenzhen stock ships in 1-2 business days; TI authorized channel replenishment is 5-10 days.
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