LM832N National Semiconductor, LM832N Datasheet

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LM832N

Manufacturer Part Number
LM832N
Description
LM832 Dynamic Noise Reduction System DNR
Manufacturer
National Semiconductor
Datasheet
C 1995 National Semiconductor Corporation
LM832 Dynamic Noise Reduction System DNR
General Description
The LM832 is a stereo noise reduction circuit for use with
audio playback systems The DNR system is noncomple-
mentary meaning it does not require encoded source mate-
rial The system is compatible with virtually all prerecorded
tapes and FM broadcasts Psychoacoustic masking and an
adaptive bandwidth scheme allow the DNR to achieve 10
dB of noise reduction DNR can save circuit board space
and cost because of the few additional components re-
quired
The LM832 is optimized for low voltage operation with input
levels around 30 mVrms
For higher input levels use the LM1894
DNR is a registered trademark of National Semiconductor Corporation
The DNR system is licensed to National Semiconductor Corp under U S patent 3 678 416
and 3 753 159
A trademark and licensing agreement is required for the use of this product
Application Circuit
TL H 5176
FIGURE 1 Component Hook-up for Stereo DNR System
Order Number LM832M See NS Package M14A
Order Number LM832N See NS Package N14A
Features
Y
Y
Y
Y
Y
Y
Y
Y
Y
Applications
Y
Y
Y
Y
Low voltage battery operation
Non-complementary noise reduction ‘‘single ended’’
Low cost external components no critical matching
Compatible with all prerecorded tapes and FM
10 dB effective tape noise reduction CCIR ARM
weighted
Wide supply range 1 5V to 9V
150 mVrms input overload
No royalty requirements
Cascade connection for 17 dB noise reduction
Headphone stereo
Microcassette players
Radio cassette players
Automotive radio tape players
RRD-B30M115 Printed in U S A
August 1989
TL H 5176 – 1

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LM832N Summary of contents

Page 1

... Y No royalty requirements Y Cascade connection for 17 dB noise reduction Y Applications Headphone stereo Y Microcassette players Y Radio cassette players Y Automotive radio tape players Y Order Number LM832M See NS Package M14A Order Number LM832N See NS Package N14A August 1989 TL H 5176 – 1 RRD-B30M115 Printed ...

Page 2

... Pin 10 Change BW Min to Max RPKD Note 1 For operation in ambient temperature above 25 C the device must be derated based on a 150 C maximum junction temperature and a thermal resistance junction to ambient as follows LM832N LM832M-115 Note 2 To force the DNR system into maximum bandwidth connect a 2k resistor from pin 9 to GND AC ground pin 9 or pin 6 to select minimum bandwidth To ...

Page 3

... FM or tape sources Failure to use the correct values may result in degraded performance and therefore the application may not be approved for DNR trademark usage Please contact National Semiconductor for more information and technical assistance ...

Page 4

Typical Performance Characteristics TL H 5176– 2 FIGURE 2 Supply current vs supply voltage TL H 5176– 5 FIGURE 5 Output level change vs supply voltage TL H 5176– 8 FIGURE 8 Output vs frequency and control path signal TL ...

Page 5

Circuit Operation The LM832 has two signal paths a main signal path and a bandwidth control path The main path is an audio low pass filter comprised block with a variable current and a m unity gain ...

Page 6

Application Hints (Continued) FIGURE 12 Bar Graph Display of Peak Detector Voltage FIGURE 13 Technique for Measuring S N Improvement of the DNR System CASCADE CONNECTION Additional noise reduction can be obtained by cascading the DNR filters With two filters ...

Page 7

Application Hints (Continued) FIGURE 15 Monaural Cascade Connection FM STEREO When using the DNR system with FM stereo as the audio source it is important to eliminate the ultrasonic frequencies that accompany the audio If the radio has a multiplex ...

Page 8

LM832 Simple Circuit Schematic 8 ...

Page 9

9 ...

Page 10

... National does not assume any responsibility for use of any circuitry described no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications Order LM832M NS Package Number M14A Order LM832N NS Package Number N14A 2 A critical component is any component of a life ...

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