SSM2166SZ

Overview

The SSM2166 is a microphone preamplifier with variable compression and noise gating. It operates on a single 5 V supply (4.5 V to 5.5 V) within a 14-lead SOIC package. The device features a voltage-controlled amplifier providing up to 60 dB of dynamic gain range and a fixed gain adjustment from 0 dB to 20 dB. Input impedance is 180 kΩ, while output impedance is 75 Ω. It delivers a bandwidth of 20 kHz (±1 dB) with a typical voltage noise density of 17 nV/√Hz at 15:1 compression. Total harmonic distortion plus noise is typically 0.25% at 1 kHz. Quiescent current is 7.5 mA to 10 mA, reducing to under 100 µA in power-down mode.

Feature Summary

• Integrates complete microphone conditioning including amplification, limiting, variable compression, and downward expansion.
• Features an automatic limiting function that prevents analog-to-digital converter overload and eliminates popping sounds.
• Includes a downward expander to prevent the amplification of background noise or hum during silent periods.
• Provides adjustable parameters for compression ratio, rotation point, and noise gate threshold via external resistors.

Applications

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

Procurement Notes

Verify the specific ordering suffix matches the required packaging configuration. Confirm the component meets RoHS compliance requirements for your assembly process. Ensure the selected variant supports the extended industrial temperature range if operating conditions exceed standard commercial limits. Cross-reference the manufacturer part number with authorized distributors to confirm availability and authenticity before finalizing procurement plans.

Selection Notes

Select this component when designing voice-band audio systems requiring integrated signal conditioning. It is suitable for applications needing optimized signal levels prior to digitization without additional digital domain processing. Consider the external resistor network requirements for setting compression ratios and thresholds. Verify that the single 5 V supply capability aligns with the system power architecture.

Part Context

This device belongs to the Analog Devices audio interface family, specifically designed for computer audio systems. It serves as a companion product for audio codecs by ensuring optimal signal levels before digitization. The integration of a voltage-controlled amplifier and rms detector allows for flexible gain control and dynamic range management in compact form factors.

Replacement Considerations

No public confirmed substitute part numbers are available in the provided documentation.

FAQ

How is the compression ratio adjusted?

The compression ratio is set by connecting a single external resistor between the COMP RATIO SET pin and ground. Values ranging from approximately 0.17 kΩ to higher resistances allow ratios from 1:1 to over 15:1.

What is the function of the Power-Down pin?

Connecting the Power-Down pin to the positive supply reduces the device supply current to less than 100 µA. For normal operation, this pin should be connected to ground.

How does the noise gate operate?

The noise gate acts as a downward expander that prevents the amplification of signals below a user-defined threshold. This threshold is set externally via a resistor connected to the NOISE GATE SET pin.