SSM2166SZ-REEL

Overview

The SSM2166SZ-REEL is a microphone preamplifier with variable compression and noise gating manufactured by Analog Devices Inc. It operates on a single 5 V supply (4.5 V to 5.5 V) within an SOIC-14 package. The device features a voltage-controlled amplifier providing up to 60 dB of dynamic gain range, adjustable compression ratios from 1:1 to over 15:1, and a downward expander for noise reduction. Key electrical parameters include a 180 kΩ input impedance, 75 Ω output impedance, and a 20 kHz bandwidth. It functions across an extended industrial temperature range of −40°C to +85°C.

Feature Summary

• Integrates a complete microphone conditioning solution including amplification, limiting, variable compression, and downward expansion.
• Features a low-noise voltage-controlled amplifier with automatic gain control to maintain set compression characteristics.
• Includes an active power-down mode that significantly reduces supply current consumption.
• Provides user-adjustable thresholds for noise gating, rotation point, and compression ratio via external components.

Applications

• Microphone preamplifiers and processors
• Computer sound cards
• Public address and paging systems
• Communication headsets
• Telephone conferencing equipment

Procurement Notes

Verify the specific suffix REEL against the manufacturer's ordering guide to confirm tape-and-reel packaging specifications. Ensure the component meets RoHS compliance requirements for your assembly process. Confirm availability status as distribution channels may report limited stock levels. Validate that the SOIC-14 footprint matches your PCB design constraints before finalizing procurement orders.

Selection Notes

Select this component when designing voice-band audio systems requiring integrated signal conditioning. It is suitable for applications needing automatic limiting to prevent ADC overload and noise gating to eliminate hum. Consider the external resistor requirements for setting compression ratios and time constants. Ensure the single 5 V supply capability aligns with your system power architecture.

Part Context

This part belongs to the SSM2166 family of audio interface devices designed for computer audio systems. It serves as a companion product for audio codecs, optimizing signal levels prior to digitization. The device eliminates the need for additional analog gain or attenuation stages in the digital domain, thereby preserving speech recognition accuracy and reducing overall system noise.

Replacement Considerations

Consult the official datasheet revision history for any die replacements or pin-compatible alternatives. Verify functional equivalence regarding compression algorithms and noise gate thresholds if substituting with other microphone preamplifiers. Ensure thermal resistance characteristics match your board layout requirements.

FAQ

How is the compression ratio configured?

The compression ratio is set externally by connecting a resistor between the COMP RATIO SET pin (Pin 10) and ground. Values can range from 1:1 to over 15:1.

What is the function of the Power Down pin?

Connecting Pin 12 to the positive supply activates the power-down mode, reducing supply current to less than 100 μA. Connecting it to ground enables normal operation.

How does the noise gate operate?

The device includes a downward expander that prevents amplification of signals below a user-defined threshold. This threshold is set via a resistor connected to the NOISE GATE SET pin.