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.)

a

HUSH Stereo Noise Reduction System

with Adaptive Threshold

SSM2000

© Analog Devices, Inc., 1996

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 617/329-4700

Fax: 617/326-8703

PIN CONFIGURATION

24-Lead Plastic DIP

24-Lead SOIC

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TOP VIEW

(Not to Scale)

NC = NO CONNECT

L IN

R VCF C2

R VCF C1

R OUT

L OUT

R IN

L VCF C1

L VCF C2

NC

DIGITAL GND

V–

V+

ACOM

VCA PORT

VCF DET IN

SUM OUT

VCA DET IN

AUTO THRESHOLD CAP

DEFEAT

MUTE

VCF DET CAP

VCA DET CAP

DEFAULT THRESHOLD

NC

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

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

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L IN

R VCF CAP 2

R VCF CAP 1

R OUT

L OUT

R IN

L VCF CAP 1

L VCF CAP 2

DIGITAL GND

V–

V+

ANALOG COMMON (V+/2)

VCA CONTROL PORT

VCF DET IN

SUM OUT

VCA DET IN

AUTO

THRESHOLD CAP

DEFEAT

MUTE

VCF DET TC

VCA DET TC

DEFAULT

1k

Ω

2nF

500

Ω

20nF

3µF

20nF

1.0µF

3.3µF

6.8µF

6.8µF

1nF

0.22µF

NOTES:

1nF

SSM2000

Figure 1. Typical Basic Application

GENERAL DESCRIPTION

The SSM2000 is an advanced audio noise reduction system

based on proprietary HUSH

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.