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LM381/LM381A Low Noise Dual Preamplifier
LM381/LM381A Low Noise Dual Preamplifier
July 1987
General Description
The LM381/LM381A is a dual preamplifier for the amplification of low level signals in applications requiring optimum
noise performance. Each of the two amplifiers is completely
independent, with individual internal power supply decoupler-regulator, providing 120 dB supply rejection and 60 dB
channel separation. Other outstanding features include high
gain (112 dB), large output voltage swing (V
and wide power bandwidth (75 kHz, 20 Vp-p). The LM381/
CC
b
2V) p-p,
LM381A operates from a single supply across the wide
range of 9V to 40V.
Either differential input or single ended input configurations
may be selected. The amplifier is internally compensated
with the provision for additional external compensation for
narrow band applications. For additional information see
AN-64, AN-104.
Schematic Diagram
Features
Y
Low noise Ð 0.5 mV total input noise
Y
High gain Ð 112 dB open loop
Y
Single supply operation
Y
Wide supply range 9V –40V
Y
Power supply rejection Ð 120 dB
Y
Large output voltage swing (V
Y
Wide bandwidth 15 MHz unity gain
Y
Power bandwidth 75 kHz, 20 Vp-p
Y
Internally compensated
Y
Short circuit protected
CC
b
2V)p-p
TL/H/7841– 1
C
1995 National Semiconductor Corporation RRD-B30M115/Printed in U. S. A.
TL/H/7841
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Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage
Power Dissipation (Note 1) 1.56 W
a
40V
Operating Temperature Range 0
Storage Temperature Range
Ctoa70§C
§
b
65§Ctoa150§C
Lead Temperature (Soldering, 10 sec.) 260§C
Electrical Characteristics T
A
e
25§C, V
e
14V, unless otherwise stated.
CC
Parameter Conditions Min Typ Max Units
Voltage Gain Open Loop (Differential Input), fe100 Hz 160,000 V/V
Open Loop (Single Ended), fe100 Hz 320,000 V/V
Supply Current VCC9V to 40V, R
L
e %
10 mA
Input Resistance
(Positive Input) 100 kX
(Negative Input)
200 kX
Input Current
(Negative Input) 0.5 mA
Output Resistance Open Loop 150 X
Output Current Source 8 mA
Sink 2 mA
Output Voltage Swing Peak-to-Peak V
b
2V
CC
Unity Gain Bandwidth 15 MHz
Power Bandwidth 20 VPP(V
e
24V) 75 kHz
CC
Maximum Input Voltage Linear Operation 300 mVrms
Supply Rejection Ratio fe1 kHz 120 dB
Channel Separation fe1 kHz 60 dB
Total Harmonic Distortion 60 dB Gain, fe1 kHz 0.1 %
Total Equivalent Input R
Noise Input, Flat Gain Circuit, A
LM381A 0.5 0.7 mVrms
e
60X, 10 –10,000 Hz (Single Ended
S
e
V
1000)
LM381 0.5 1.0 mVrms
Note 1: 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
C/W junction to ambient.
of 80
§
Connection Diagram
Dual-In-Line Package
TL/H/7841– 2
Top View
Order Number LM381N or LM381AN
See NS Package Number N14A
2
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Typical Applications
Typical Tape Playback Amplifier
Typical Magnetic Phono Preamp
Two-Pole Fast Turn-On NAB Tape Preamp
TL/H/7841– 3
TL/H/7841– 5
Ultra-Low Distortion Amplifier
e
(A
10, THDk0.05%, V
V
OUT
Audio Mixer
TL/H/7841– 4
TL/H/7841– 6
e
3V
)
RMS
TL/H/7841– 7
3
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Typical Performance Characteristics
Large Signal Frequency
Response
% Distortion Channel Separation PSRR vs Frequency
Gain and Phase Response Noise Voltage vs Frequency Noise Current vs Frequency
VCCvs I
CC
P-P Output Voltage
VCCSwing vs
Pulse Response
4
TL/H/7841– 8
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5
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Physical Dimensions inches (millimeters)
Order Number LM381N or LM381AN
LM381/LM381A Low Noise Dual Preamplifier
Molded Dual-In-Line Package (N)
NS Package Number N14A
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL
SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or 2. A critical component is any component of a life
systems which, (a) are intended for surgical implant support device or system whose failure to perform can
into the body, or (b) support or sustain life, and whose be reasonably expected to cause the failure of the life
failure to perform, when properly used in accordance support device or system, or to affect its safety or
with instructions for use provided in the labeling, can effectiveness.
be reasonably expected to result in a significant injury
to the user.
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Corporation Europe Hong Kong Ltd. Japan Ltd.
1111 West Bardin Road Fax: (
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