SSM2167-1RMZ-R7

The SSM2167 microphone preamplifier operates at a single 3 V voltage.

The compression ratio in the SSM2167 microphone preamplifier is set by a single resistor, which can be adjusted to vary the ratio from 1:1 to over 10:1 relative to the fixed rotation point. This allows for flexibility in setting the compression ratio and the time constant of the level detector, making it easy to integrate into a wide variety of microphone conditioning applications . The SSM2167 is a complete microphone signal conditioning system that provides amplification, limiting, variable compression, and noise gate on a single integrated circuit. It is designed primarily for voice-band applications and offers user-adjustable compression ratio, noise gate threshold, and two different fixed gains to optimize circuit operation for various applications . In summary, the compression ratio in the SSM2167 microphone preamplifier is set by a single resistor, allowing for flexibility in adjusting the ratio, and it offers various features to optimize signal levels and performance in microphone conditioning applications

The purpose of the downward expander (noise gate) in the SSM2167 microphone preamplifier is to set a threshold for downward expansion, which allows for signals below a certain level to be attenuated, preventing noise interference. This threshold can be set between -40 dBV and -55 dBV using an external resistor connected to Pin 7 (GATE THRS) and V DD. The downward expansion threshold is inversely proportional to the resistance value, with lower resistance values setting the threshold at higher levels and vice versa. It is important not to use a resistor value greater than 5 kΩ to avoid issues with the noise floor of the SSM2167. The downward expansion feature ensures that small input signals cause a proportional decrease in output level, maintaining a consistent gain for different input signal levels. Additionally, the SSM2167 provides a digital power-down feature to reduce device supply current when not in use.