The SSM2166 integrates a complete and flexible solution for conditioning microphone inputs in 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 15:1 relative to a user-defined rotation point; signals above the rotation point are limited to prevent overload and to eliminate popping. In the 1:1 compression setting, the SSM2166 can be programmed with a fixed gain of up to 20 dB; this gain is in addition to the variable gain in other compression settings. The input buffer can also be configured for front-end gains of 0 dB to 20 dB. A downward expander (noise gate) prevents amplification of 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 that could add noise or impair accuracy of speech recognition algorithms. The compression ratio and time constants are set externally. A high degree of flexibility is provided by the VCA gain, rotation point, and noise gate adjustment pins.

The SSM2166 is an ideal companion product for audio codecs used in computer systems, such as the AD1845. The SSM2166 is available in a 14-lead SOIC package and is guaranteed for operation over the extended industrial temperature range of −40°C to +85°C.

Applications

Microphone preamplifiers/processors

Computer sound cards

Public address/paging systems

Communication headsets

Telephone conferencing

Guitar sustain effects generators

Computerized voice recognition

Surveillance systems

Karaoke and DJ mixers

Data Sheet, Rev. C, 5/08

Part#	Instructions/Cycles	DAC DNR (dB)	DAC THD+N @ 1 kHz (-3dB)	ADC DNR (dB)	ADC THD+N (dB)	Digital I/O Channels	Analog I/O Channels	Product Description	Price* (1000-4999)
AD1940	1,536	n/a	n/a	-	-	16/16	0/0	SigmaDSP Multichannel 28-/56-Bit Audio Processor w/ 4-Wire SPI ® control interface.	$8.09
AD1941	1,536	n/a	n/a	-	-	16/16	0/0	SigmaDSP Multichannel 28-/56-Bit Audio Processor w/ 2-wire I2C ® control interface.	$8.35
AD1953	512	112	100	-	-	4/6	0/3	SigmaDSP 3 Ch, 26-/48-Bit Processing D/A	$7.06
AD1954	512	112	100	-	-	4/2	0/3	SigmaDSP 3 Ch, 26-/48-Bit Processing D/A	$7.06
ADAU1401	1,024	104	90	100	-83	8/8	2/4	28/56-Bit Automotive Audio Processor with Two ADCs and Four DACs	-
ADAU1701	1,024	104	90	100	-83	8/8	2/4	SigmaDSP® 28/56-Bit Audio Processor with Two ADCs and Four DACs	$4.47
ADAU1702	512	104	90	100	-83	8/8	2/4	SigmaDSP 28/56-Bit Audio Processor with 2 ADC/4 DAC	$3.53

* The pricing listed here is provided only for budgetary purposes as recommended list price in U.S. Dollars in the United States ex factor per unit for the stated volume. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.
** Pricing is currently unavailable. Click on the product number to see the Product Page for additional information.

The model number is a specific version of a generic that can be purchased or sampled.

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• Pre-Release: The model has not been released to general production, but samples may be available.
• Production: The model is currently being produced, and generally available for purchase and sampling.
• Last Time Buy: The model has been scheduled for obsolescence, but may still be purchased for a limited time.
• Obsolete: The specific part is obsolete and no longer available. Other models listed in the table may still be available (if they have a status that is not obsolete).

The package for this IC (i.e. DIP, SOIC, BGA). An Evaluation Board is a board engineered to show the performance of the model, the part is included on the board.

For detailed drawings and chemical composition please consult our  Package Site

Pin Count is the number of pins, balls, or pads on the device. Pin-out diagrams & pin function descriptions may be found in the datasheet.

This is the acceptable operating range of the device. The various ranges specified are as follows:

• Commercial: 0 to +70 degrees Celsius
• Military : -55 to +125 degrees Celsius
• Industrial: Temperature ranges may vary by model. Please consult the datasheet for more information.
• Automotive: -40 to +125 degrees Celsius

The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

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Due to environmental concerns, ADI offers many of our products in lead-free versions. For more information about lead-free parts, please consult our Pb (Lead) free information page.