Datasheet SSM2166 (Analog Devices) - 5

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Data Sheet SSM2166 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS GND 1 14 V+ GAIN ADJUST 2 13 OUTPUT VCAIN 3 12 POWER DOWN SSM2166 VCAR 4 TOP VIEW 11 ROTATION SET BUF OUT (Not to Scale) 5 10 COMP RATIO SET –IN 6 9 NOISE GATE SET
3 00 7-
AUDIO +IN 7 8 AVG CAP
35 00 Figure 3. Pin Configuration
Table 4. Pin Function Descriptions Pin No. Mnemonic Description
1 GND Ground. 2 GAIN ADJUST VCA Gain Adjust Pin. A resistor from this pin to ground sets the fixed gain of the VCA. To check the setting of this pin, make sure the compression ratio set pin (Pin 10) is grounded for no compression. The gain can be varied from 0 dB to 20 dB. For 20 dB, leave the pin open. For 0 dB of fixed gain, a typical resistor value is approximately 1 kΩ. For 10 dB of fixed gain, the resistor value is approximately 2 kΩ to 3 kΩ. For resistor values <1 kΩ, the VCA can attenuate or mute (see Figure 6). 3 VCAIN VCA Input Pin. A typical connection is a 10 μF capacitor from the buffer output pin (Pin 5) to this pin. 4 VCAR Inverting Input to the VCA. This input can be used as a nonground reference for the audio input signal (see the Applications Information section). 5 BUF OUT Input Buffer Amplifier Output Pin. This pin must not be loaded by capacitance to ground. 6 −IN Inverting Input to the Buffer. A 10 kΩ feedback resistor, R1, from the buffer output (Pin 5) to this input pin and a resistor, R2, from this pin through a 1 μF capacitor to ground give gains of 6 dB to 20 dB for R2 = 10 kΩ to 1.1 kΩ. 7 AUDIO +IN Input Audio Signal. AC-coupled (0.1 μF typical) the input signal into this pin. 8 AVG CAP Detector Averaging Capacitor. A capacitor, 1 μF to 22 μF, to ground from this pin is the averaging capacitor for the detector circuit. 9 NOISE GATE SET Noise Gate Threshold Set Point. A resistor to V+ sets the level below which input signals are downward expanded. For a 0.7 mV threshold, the resistor value is approximately 380 kΩ. Increasing the resistor value reduces the threshold (see Figure 5). 10 COMP RATIO SET Compression Ratio Set Pin. A resistor to ground from this pin sets the compression ratio, as shown in Figure 2. Figure 19 gives resistor values for various rotation points. 11 ROTATION SET Rotation Point Set Pin. This pin is set by adding a resistor to the positive supply. This resistor together with the gain adjust pin determines the onset of limiting. A typical value for this resistor is 17 kΩ for a 100 mV rotation point. Increasing the resistor value reduces the level at which limiting occurs (see Figure 9). 12 POWER DOWN Power-Down Pin. Connect this pin to ground for normal operation. Connect this pin to the positive supply for power-down mode. 13 OUTPUT Output Signal. 14 V+ Positive Supply, 5 V Nominal. Rev. F | Page 5 of 13 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM AND TYPICAL SPEECH APPLICATION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION APPLICATIONS INFORMATION SIGNAL PATH LEVEL DETECTOR CONTROL CIRCUITRY Compression Ratio Rotation Point VCA Gain Setting and Muting Downward Expansion Threshold POWER-DOWN FEATURE PCB LAYOUT CONSIDERATIONS OUTLINE DIMENSIONS ORDERING GUIDE