Wing LM386-1 Low voltage adio power amplifier Datasheet

Low Voltage
Audio Power Amplifier
LM386-1
Low Voltage Audio Power Amplifier
General Description
Features
The LM386-1 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 pins 1 and 8 will increase the
gain to any value from 20 to 200.
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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 volt
supply, making the WS386M-1 ideal for battery operation
Applications
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AM-FM radio amplifiers
Portable tape player amplifiers
Intercoms
TV sound systems
Line drivers
Ultrasonic drivers
Small servo drivers
Power converters
Battery operation
Minimum external parts
Wide supply voltage range: 4V–12V
Low quiescent current drain: 4mA
Voltage gains from 20 to 200
Ground referenced input
Self-centering output quiescent voltage
Low distortion: 0.2% (AV = 20, VS = 6V, RL = 8Ω, PO =
125mW, f = 1kHz)
n Available in 8 pin SOP package and DIP package
Ordering Information
PART NO.
PACKAGE
SOP-8
LM386M-1
DIP-8
LM386N-1
Equivalent Schematic and Connection Diagrams
Small Outline,
Dual in Line Package
Pin Connection
Wing Shing Computer Components Co., (H.K.)Ltd.
Homepage: http://www.wingshing.com
Tel:(852)2341 9276 Fax:(852)2797 8153
E-mail: [email protected]
8-1
LM386-1
Soldering Information
Absolute Maximum Ratings
Supply Voltage
(WS386-1)
Dual-In-Line Package
Soldering (10 sec)
Small Outline Package
(SOIC )
Vapor Phase (60 sec)
Infrared (15 sec)
15V
Package Dissipation(Note3)
(WS386N)
1.25W
(WS386M)
0.73W
Input Voltage
+- .4V
- 65 C to +150 C
Storage Temperature
Operating Temperature
Junction Temperature
+260˚C
+215˚C
+220˚C
0 C to+70 C
+150 C
Electrical Characteristics (Notes 1, 2)
TA = 25˚C ,Vcc=6V,R =8 ,f=1KHZ, unless otherwise specified
Parameter
Conditions
Min
Typ
Max
Units
Operating Supply Voltage (VS)
12
4
Quiescent Current (IQ)
VS = 6V, VIN = 0
4
8
V
mA
Output Power (POUT)
V S = 6V, RL = 8Ω, THD = 10%
250
325
700
Vs = 6V,10uF from Pin 1 to 8
50
0
V s = 9V,RL =8 , THD =10%
Bandwidth (BW)
Voltage Gain (AV)
Bandwidth (BW)
Total Harmonic Distortion (THD)
VS = 6V, f = 1 kHz
Pins 1 and 8 Open
mW
60
kHz
26
dB
10 µF from Pin 1 to 8
46
dB
VS = 6V, Pins 1 and 8 Open
300
kHz
VS = 6V, RL = 8Ω, POUT = 125 mW
0.2
%
50
dB
50
kΩ
250
nA
f = 1 kHz, Pins 1 and 8 Open
Power Supply Rejection Ratio (PSRR)
VS = 6V, f = 1 kHz, CBYPASS = 10 µF
Pins 1 and 8 Open, Referred to Output
Input Resistance (RIN)
Input Bias Current (IBIAS)
VS = 6V, Pins 2 and 3 Open
Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified.
Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit is
given, however, the typical value is a good indication of device performance.
Note 3: For operation in ambient temperatures above 25˚C, the device must be derated based on a 150˚C maximum junction temperature and
a thermal resistance of 170˚C/W for the small outline package.
8-2
LM386-1
Application Hints
GAIN CONTROL
To make LM386-1 a more versatile amplifier, two pins (1
and 8) are provided for gain control. With pins 1 and 8 open
the 1.35 kΩ resistor sets the gain at 20 (26 dB). If a capacitor
is put from pin 1 to 8, bypassing the 1.35 kΩ resistor, the
gain will go up to 200 (46 dB). 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 250 nA, so the inputs are at about 12.5 mV
when left open. If the dc source resistance driving the LM386
is higher than 250 kΩ it will contribute very little additional
offset (about 2.5 mV at the input, 50 mV 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 2.5 mV
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 LM386-1 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 0.1 µF capacitor or
a short to ground depending on the dc source resistance on
the driven input.
Pad Location
8
1
7
6
5
90
90
2
4B
Y
3
0
X
4A
Chip size 1.4 x 1.6 mm
Pad Location Coordinates
Pad N
Pad Name
1
2
3
4A
4B
5
6
7
8
Gain
-input
+input
GND
GND
VOUT
VCC
BYPASS
Gain
8-3
Coordinates
X
120
120
120
550
600
600
750
440
120
Y
975
665
100
100
390
1015
1405
1405
1405
LM386-1
Typical Performance Characteristics
Quiescent Supply Current
vs Supply Voltage
Voltage Gain vs Frequency
Device Dissipation vs Output
Power — 4Ω Load
Power Supply Rejection Ratio
(Referred to the Output)
vs Frequency
Peak-to-Peak Output Voltage
Swing vs Supply Voltage
Distortion vs Frequency
Distortion vs Output Power
Device Dissipation vs Output
Power — 8Ω Load
Device Dissipation vs Output
Power — 16Ω Load
8-4
LM386-1
Typical Applications
Amplifier with Gain = 200
Amplifier with Gain = 20
Minimum Parts
Low Distortion Power Wienbridge Oscillator
Amplifier with Gain = 50
Square Wave Oscillator
Amplifier with Bass Boost
8-5
LM386-1
Typical Applications
(Continued)
Frequency Response with Bass Boost
AM Radio Power Amplifier
Note 4: Twist Supply lead and supply ground very tightly.
Note 5: Twist speaker lead and ground very tightly.
Note 6: Ferrite bead in Ferroxcube K5-001-001/3B with 3 turns of wire.
Note 7: R1C1 band limits input signals.
Note 8: All components must be spaced very closely to IC.
8-6
Physical Dimensions
inches (millimeters) unless otherwise noted (Continued)
Dual-In-Line Package
LM386N-1
8-7
LM386-1
Physical Dimensions
inches (millimeters) unless otherwise noted
SO Package
LM386M-1
8-8
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