SSM2166S

Overview

The SSM2166S 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) and features a 14-lead SOIC package. Key electrical parameters include a voltage noise density of 17 nV/√Hz at 15:1 compression, a total harmonic distortion plus noise of 0.25% to 0.5%, and an input impedance of 180 kΩ. The device provides a gain bandwidth product of 30 MHz, a power supply rejection ratio of 50 dB, and a quiescent supply current of 7.5 mA to 10 mA. It functions within 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 dynamic gain adjustment to maintain set compression characteristics.
• Includes an automatic limiting feature to prevent analog-to-digital converter overload and eliminate popping sounds.
• Provides a power-down mode that significantly reduces supply current consumption.

Applications

• Microphone preamplifiers and processors for computer sound cards
• Public address and paging systems
• Communication headsets and telephone conferencing equipment
• Computerized voice recognition systems
• Surveillance systems

Procurement Notes

Verify the specific suffix 'S' corresponds to the SOIC-14 package variant when sourcing. Confirm the operating temperature range requirements match the specified industrial limits. Ensure the single 5 V supply rail aligns with system design constraints. Check for any specific revision history updates in the latest datasheet regarding pin configurations or performance characteristics before finalizing procurement.

Selection Notes

Select this component for applications requiring integrated microphone signal conditioning without external discrete components. The adjustable compression ratio and noise gate threshold allow customization for various acoustic environments. Consider the 14-lead SOIC package for surface-mount assembly compatibility. Evaluate the 30 MHz gain bandwidth product against the required audio frequency response needs.

Part Context

The SSM2166 series serves as a versatile microphone preamplifier designed primarily for processing microphone inputs in computer audio systems. It improves vocal clarity in communications and public address applications. The device acts as an ideal companion for audio codecs used in digital systems, optimizing signal levels prior to digitization to eliminate the need for additional gain or attenuation in the digital domain.

Replacement Considerations

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

FAQ

How is the compression ratio adjusted?

The compression ratio is set externally by connecting a resistor between the COMP RATIO SET pin (Pin 10) and ground. Lowering the resistance value results in smaller compression ratios.

What is the function of the Noise Gate Set pin?

The NOISE GATE SET pin (Pin 9) allows the user to set the downward expansion threshold. A resistor connected to the positive supply determines the level below which input signals are expanded, effectively acting as a noise gate.

How does the Power Down feature work?

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