SSM2000_15 Datasheet, PDF (1/16 Pages) Analog Devices – HUSH Stereo Noise Reduction System with Adaptive Threshold

a
HUSH Stereo Noise Reduction System
with Adaptive Threshold
SSM2000
FEATURES
Up to 25 dB of Noise Reduction from Virtually Any
Audio Source without Sonic Artifacts
“Single-Ended” Operation Eliminates Need for Encode-
Decode Process
Adaptive Threshold Dynamically Adjusts to Changing
Nominal Signal Levels
Effectively Decodes Dolby B^® Encoded Sources
Direct VCA Control Port Access for Additional Level
Control Functionality
Logic-Controllable Bypass and Muting
100 dB Dynamic Range (Noise Reduction OFF)
0.02% Typical THD+N (@ 1 kHz, Noise Reduction OFF)
+7 V to +18 V Operation
No Royalty Requirements
APPLICATIONS
Auto Radio Sound Processing
Multimedia PC Sound Cards
Television Sound Processing
Cassette Tape Players
AM/FM Receivers
Telephone & Wireless Links
Professional Audio
GENERAL DESCRIPTION
The SSM2000 is an advanced audio noise reduction system
based on proprietary HUSH^® circuitry. HUSH combines a dy-
namic filter and downward expander to provide a high level of
effectiveness without the sonic artifacts normally associated with
noise reduction systems. In addition, an Adaptive Threshold
circuit detects nominal signal levels and dynamically adjusts
both thresholds, thereby providing optimal results regardless of
program source. Since it is a single-ended system, HUSH can
be used on virtually any audio source, including audio and
video tapes, radio and television broadcasts, or any other source
with objectionable noise. The SSM2000 can be used with
Dolby B encoded sources with excellent results. A key feature is
direct access to the Voltage Controlled Amplifier port enabling
additional functions such as dc volume control, automatic level-
ing, compression, etc. with minimal external circuitry.
Dolby B is a registered trademark of Dolby Laboratories, Inc.
HUSH is a registered trademark of Rocktron Corporation.
PIN CONFIGURATION
24-Lead Plastic DIP
24-Lead SOIC
L IN 1
24 L OUT
R IN 2
23 R OUT
L VCF C1 3
22 R VCF C1
L VCF C2 4
21 R VCF C2
V+ 5
20 V–
SSM2000
ACOM 6 _{TOP VIEW} 19 DIGITAL GND
VCA PORT 7 ^{(Not to Scale)} 18 NC
VCF DET IN 8
17 MUTE
SUM OUT ⁹
16 DEFEAT
VCA DET IN 10
15 AUTO THRESHOLD CAP
VCF DET CAP 11
14 DEFAULT THRESHOLD
VCA DET CAP 12
13 NC
NC = NO CONNECT
L IN
R IN
6.8µF
1
6.8µF
2
L VCF CAP 1
L VCF CAP 2
3
1nF
4
24
L OUT
23
R OUT
22
1nF
21
R VCF CAP 1
R VCF CAP 2
V+
ANALOG COMMON (V+/2)
5
20
SSM2000
6
19
V–
DIGITAL GND
VCA CONTROL PORT
7
VCF DET IN
20nF
SUM OUT
VCA DET IN
20nF
500Ω
2nF
8
1kΩ
9
3µF
10
1.0µF
VCF DET TC
11
3.3µF
VCA DET TC
12
18
DO NOT CONNECT¹
17
MUTE
16
0.22µF
15
DEFEAT
AUTO
THRESHOLD CAP
14
DEFAULT
THRESHOLD²
13
DO NOT CONNECT¹
NOTES:
1_{MAKE NO CONNECTION TO PINS 13 AND 18}
2_{DEFAULT THRESHOLD. NORMALLY CONNECTED TO ANALOG COMMON}
Figure 1. Typical Basic Application
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices. (See page 16.)
© Analog Devices, Inc., 1996
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