Analog Devices SSM2167-2RM, SSM2167-1RM Datasheet

Low Voltage Microphone

INPUT – dB

OUTPUT – dB

LIMITING

REGION

LIMITING

THRESHOLD

(ROTATION POINT)

COMPRESSION

REGION

1

r

1

1

DOWNWARD

EXPANSION

THRESHOLD

(NOISE GATE)

DOWNWARD

EXPANSION

REGION

V

DE

V

RP

VCA GAIN

Preamplifier with Variable

a

FEATURES
Complete Microphone Conditioner in a 10-Lead Package
Single 3 V Operation
Low Shutdown Current < 2 ␮A
Adjustable Noise Gate Threshold
Adjustable Compression Ratio
Automatic Limiting Feature Prevents ADC Overload
Low Noise and Distortion: 0.2% THD + N
20 kHz Bandwidth

APPLICATIONS
Desktop, Portable, or Palmtop Computers
Telephone Conferencing
Communication Headsets
Two-Way Communications
Surveillance Systems
Karaoke and DJ Mixers

GENERAL DESCRIPTION

The SSM2167 is a complete and flexible solution for conditioning
microphone inputs in personal electronics and computer audio
systems. It is also excellent for improving vocal clarity in communi­cations and public address systems. A low noise voltage controlled
amplifier (VCA) provides a gain that is dynamically adjusted by a
control loop to maintain a set compression characteristic. The
compression ratio is set by a single resistor and can be varied from
1:1 to over 10:1 relative to the fixed rotation point. Signals above
the rotation point are limited to prevent overload and to eliminate
“popping.” A downward expander (noise gate) prevents amplifica­tion of background noise or hum. This results in optimized signal
levels prior to digitization, thereby eliminating the need for addi­tional gain or attenuation in the digital domain. The flexibility of
setting the compression ratio and the time constant of the level
detector, coupled with two values of rotation point, make the
SSM2167 easy to integrate in a wide variety of microphone
conditioning applications.

The SSM2167 is available in two versions, with different amounts
of fixed gain. The SSM2167-1 has 18 dB of fixed gain, while
the SSM2167-2 features only 8 dB of fixed gain.

The device is available in 10-lead MSOP package, and guaranteed
for operation over the extended industrial temperature range of
–40°C to +85°C.

Compression and Noise Gating

SSM2167

PIN CONFIGURATION

10-Lead MSOP

(RM Suffix)

1

GND

2

VCA

IN

SSM2167

INPUT

3

4

5

SHUTDOWN

BUF OUT

Figure 1. General Input/Output Characteristics

10

V

DD

9

OUTPUT

8

COMPRESSION RATIO

7

GATE THRS

6

AVG CAP

REV. A

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 that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]www.analog.com
Fax: [phone] © Analog Devices, Inc., 2002

SSM2167–SPECIFICATIONS

(@ VS = 3.0 V, f = 1 kHz, RL = 100 k⍀, R
R

= 2 k⍀, unless otherwise noted.)

GATE

= 0 ⍀, TA = 25ⴗC, VIN = 100 mV rms,

COMP

Parameter Symbol Conditions Min Typ Max Unit

AUDIO SIGNAL PATH

Voltage Noise Density e

n

Noise 20 kHz Bandwidth, V
Total Harmonic Distortion + Noise THD + N V
Input Impedance Z
Output Impedance Z

IN

OUT

10:1 Compression 20 nV/√Hz

= GND –70 dBV

= 100 mV rms 0.2 %

IN

IN

100 kΩ
145 Ω

Load Drive Minimum Resistive Load 5 kΩ

Maximum Capacitive Load 2 nF
Input Voltage Range 0.4% THD 600 mV rms
Output Voltage Range 0.4% THD
SSM2167-1 700 mV rms
SSM2167-2* 700 mV rms
Gain Bandwidth Product 1:1 Compression
SSM2167-1 VCA G = 18 dB 1 MHz
SSM2167-2* VCA G = 8 dB 1 MHz

CONTROL SECTION

VCA Dynamic Gain Range 40 dB
VCA Fixed Gain
SSM2167-1 18 dB
SSM2167-2* 8dB
Compression Ratio, Min 1:1
Compression Ratio, Max See Table I for R

COMP

10:1
Rotation Point
SSM2167-1 63 mV rms
SSM2167-2* 100 mV rms
Noise Gate Range Maximum Threshold –40 dBV

POWER SUPPLY

Supply Voltage V
Supply Current I

SY

SY

2.5 5.5 V

2.3 5 mA
DC Output Voltage 1.4 V
Power Supply Rejection Ratio PSRR VSY = 2.5 V to 6 V 4.5 mV

SHUTDOWN

Supply Current I

*Preliminary

Specifications subject to change without notice.

SY

Pin 3 = GND 2 8 ␮A

–2–

REV. A

SSM2167

WARNING!

ESD SENSITIVE DEVICE

ABSOLUTE MAXIMUM RATINGS*

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V

Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V

Operating Temperature Range . . . . . . . . . . . –40°C to +85°C

Junction Temperature Range . . . . . . . . . . . . . . . . . . . . 150°C

Lead Temperature Range (Soldering, 10 sec) . . . . . . . 300°C

Package Type ␪JA* ␪

10-Lead MSOP (RM) 180 35 °C/W

*θJA is specified for worst-case conditions, i.e., θ

in 4-layer circuit board for surface-mount packages.

ESD RATINGS

883 (Human Body) Model . . . . . . . . . . . . . . . . . . . . . . 500 V

*Stresses above those listed under Absolute Maximum Ratings may cause perma-

nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those listed in the operational sections
of this specification is not implied. Exposure to absolute maximum rating condi­tions for extended periods may affect device reliability.

ORDERING GUIDE

Temperature Package Package

Model Range Description Option

SSM2167-1RM-Reel –40°C to +85°C 10-Lead Mini/micro SOIC (MSOP) RM-10
SSM2167-2RM-Reel* –40°C to +85°C 10-Lead Mini/micro SOIC (MSOP) RM-10

*Preliminary

CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although
the SSM2167 features proprietary ESD protection circuitry, permanent damage may occur on
devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.

JC

is specified for device soldered

JA

Unit

REV. A

–3–