UNISONIC TECHNOLOGIES CO.,
LM386
LOW VOLTAGE AUDIO POWER
AMPLIFIER
DESCRIPTION
The UTC
LM386
is a power amplifier, designed for use in low voltage
consumer applications. The gain is internally set to 20 to keep external
part count low, but the addition of an external resistor and capacitor
between pin 1 and pin 8 will increase the gain to any value up from 20 to
200.
The inputs are ground referenced while the output automatically biases
to one-half the supply voltage. The quiescent power drain is only 24
milliwatts when operating from a 6 voltage supply, making the LM386
ideal for battery operation.
LINEAR INTEGRATED CIRCUIT
FEATURES
*Battery Operation
*Minimum External Parts
*Wide Supply Voltage Range: 4V~12V
*Low Quiescent Current Drain:4mA
*Voltage Gains:20~200
*Ground Referenced Input
*Self-Centering Output Quiescent Voltage
*Low Distortion:0.2%(Av =20,Vs=6V,R
L
=8Ω,Po=125mW,f=1kHz)
ORDERING INFORMATION
Normal
LM386-S08-R
LM386-S08-T
LM386-P08-R
LM386-P08-T
LM386-D08-T
Ordering Number
Lead Free
LM386L-S08-R
LM386L-S08-T
LM386L-P08-R
LM386L-P08-T
LM386L-D08-T
Halogen Free
LM386G-S08-R
LM386G-S08-T
LM386G-P08-R
LM386G-P08-T
LM386G-D08-T
Package
SOP-8
SOP-8
TSSOP-8
TSSOP-8
DIP-8
Packing
Tape Reel
Tube
Tape Reel
Tube
Tube
www.unisonic.com.tw
Copyright © 2011 Unisonic Technologies Co.,
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QW-R107-007.H
LM386
PIN CONFIGURATION
LINEAR INTEGRATED CIRCUIT
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R107-007.H
LM386
BLOCK DIAGRAM
LINEAR INTEGRATED CIRCUIT
6
15K
GAIN GAIN
8
1
150
-INPUT
2
1.35K
3
+INPUT
Vs
BYPASS
7
15K
15K
5
V
OUT
50K
50K
4
GND
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R107-007.H
LM386
ABSOLUTE MAXIMUM RATINGS
PARAMETER
SYMBOL
V
CC
V
IN
LINEAR INTEGRATED CIRCUIT
RATINGS
UNIT
Supply Voltage
15
V
Input Voltage
-0.4V ~ +0.4V
V
DIP-8
1250
Power Dissipation
P
D
mW
SOP-8
600
TSSOP-8
600
Operating Temperature
T
OPR
-20 ~ +85
°C
Junction Temperature
T
J
+125
°C
Storage Temperature
T
STG
-40 ~ +150
°C
Note:1. Absolute maximum ratings are stress ratings only and functional device operation is not implied. The device
could be damaged beyond Absolute maximum ratings.
ELECTRICAL CHARACTERISTICS
(Ta=25°C, unless otherwise specified.)
PARAMETER
Operating Supply Voltage
Quiescent Current
Output Power
Voltage Gain
Bandwidth
Total Harmonic Distortion
Rejection Ratio
Input Resistance
Input Bias Current
SYMBOL
Vss
I
Q
P
OUT
G
V
BW
THD
RR
R
IN
I
BIAS
TEST CONDITIONS
Vss=6V, V
IN
=0
Vss=6V, R
L
=8Ω, THD=10%
Vss=9V, R
L
=8Ω, THD=10%
Vss=6V, f=1kHz
10μF from pin 1 to pin 8
Vss=6V , Pin1 and pin 8 open
P
OUT
=125mW, Vs=6V,f=1kHz
R
L
=8Ω pin1 and pin 8 open
Vss=6V, f=1kHz, C
BYPASS
=10μF
pin1and pin 8 open, Referred to output
Vss=6V Pin2 and pin 3 open
MIN
4
250
500
TYP
4
325
700
26
46
300
0.2
50
50
250
MAX UNIT
12
V
8
mA
mW
dB
dB
kHz
%
dB
kΩ
nA
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R107-007.H
LM386
APPLICATION NOTES
LINEAR INTEGRATED CIRCUIT
GAIN CONTROL
To make the LM386 a more versatile amplifier, two pins(1and 8) are provided for gain control. With pins 1 and 8
open the 1.35 kΩ resistor sets the gain at 20(26dB),If a capacitor is put from pin 1 to 8,bypassing the 1.35 kΩ
resistor, the gain will go up to 200(46dB).If a resistor is placed in series with the capacitor, the gain can be set to any
value from 20 to 200.Gain control can also be done by capacitively coupling a resistor (or FET) from pin 1 to ground.
Additional external components can be placed in parallel with the internal feedback resistors to tailor the gain and
frequency response for individual applications. For example we can compensate poor speaker bass response by
frequency shaping the feedback path. This is done with a series RC from pin 1 to 5 (paralleling the internal 15 kΩ
resistor). For 6 dB effective bass boost: R=15 kΩ, the lowest value for good stable operation is R=10 kΩ, if pin 8 is
open, If pins 1 and 8 are bypassed then R as low as 2 kΩ can be used. This restriction is because the amplifier is
only compensated for closed-loop gains greater than 9.
INPUT BIASING
The schematic shows that both inputs are biased to ground with a 50 kΩ resistor. The base current of the input
transistors is about 250nA, so the inputs are at about 12.5mW when left open. If the dc source resistance driving the
LM386 is higher than 250 kΩ it will contribute very little additional offset (about 2.5mW at the input, 50mW at the
output).If the dc source resistance is less than 10 kΩ,then shorting the unused input to ground will keep the offset
low (about 2.5mV at the input,50 mV at the output).For dc source resistances between these values we can
eliminate excess offset by putting a resistor from the unused input to ground, equal in value to the dc source
resistance. Of course all offset problems are eliminated if the input is capacitively coupled.
When using the LM386 with higher gains (bypassing the 1.35 kΩ resistor between pins 1 and 8)it is necessary to
bypass the unused input, preventing degradation of gain and possible instabilities. This is done with a 0.1μF
capacitor or a short to ground depending on the dc source resistance on the driven input.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R107-007.H
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