SSM2166SZ Analog Devices Inc, SSM2166SZ Datasheet - Page 9

• Manufacturer Part Number: SSM2166SZ
• Description: Audio Amp Microphone 1-CH Mono Class-AB 14-Pin SOIC N
• Manufacturer: Analog Devices Inc

Specifications of SSM2166SZ

• Package: 14SOIC N
• Function: Microphone
• Amplifier Type: Class-AB
• Typical Voltage Gain: 60 dB
• Total Harmonic Distortion Noise: 0.25@100000Ohm %
• Typical Psrr: 50 dB
• Typical Gain Bandwidth Product: 30 MHz
• Maximum Load Resistance: 100000 Ohm
• Output Type: 1-Channel Mono
• Voltage - Supply: 4.5 V ~ 5.5 V
• Features: Microphone
• Mounting Type: Surface Mount
• Package / Case: 14-SOIC (3.9mm Width), 14-SOL
• Bandwidth: 20 kHz
• Current, Supply: 7.5 mA
• Harmonic Distortion: 0.25 %
• Impedance, Thermal: 120 °C/W
• Package Type: SOIC-14
• Temperature, Operating, Range: -40 to +85 °C
• Voltage, Input: 1 V
• Voltage, Noise: 17 nV/sqrt Hz
• Voltage, Supply: 4.5 to 5.5 V
• No. Of Channels: 1
• Supply Voltage Range: 4.5V To 5.5V
• Load Impedance: 75ohm
• Operating Temperature Range: -40°C To +85°C
• Amplifier Case Style: SOIC
• No. Of Pins: 14
• Msl: MSL 1 - Unlimited
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Max Output Power X Channels @ Load: -
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

The gain of the VCA at the rotation point is set by the value of a
resistor, R
between the VCA gain and R
range can be as high as 60 dB. The VCA
inverting input terminal to the VCA. The inverting input of the
VCA is available at the VCA
impedance of 1 kΩ, as well. As a result, this pin can be used for
differential inputs or for the elimination of grounding problems
by connecting a capacitor whose value equals that used in series
with the VCA
The output impedance of the SSM2166 is typically less than 75 Ω,
and the external load on Pin 13 should be >5 kΩ. The nominal
output dc voltage of the device is approximately 2.2 V. Use a
blocking capacitor for grounded loads.
The bandwidth of the SSM2166 is quite wide at all gain settings.
The upper 3 dB point is approximately 30 kHz at gains as high as
60 dB (using the input buffer for additional gain, circuit bandwidth
is unaffected). The gain bandwidth (GBW) plots are shown in
Figure 11. The lower 3 dB cutoff frequency of the SSM2166 is
set by the input impedance of the VCA (1 kΩ) and C6. While the
noise of the input buffer is fixed, the input referred noise of the
VCA is a function of gain. The VCA input noise is designed to
be a minimum when the gain is at a maximum, thereby optimizing
the usable dynamic range of the part. A plot of wideband peak-
to-peak output noise is shown in Figure 10.
GAIN
, connected between Pin 2 and GND. The relationship
IN
pin to ground (see Figure 26 for more details).
+
R1
10kΩ
R2
10kΩ
1µF
R
AUDIO
GAIN
pin (Pin 4) and exhibits an input
+IN
is shown in Figure 6. The AGC
0.1µF
C1
–IN
IN
pin (Pin 3) is the non-
6
7
GND
Figure 16. Functional Block Diagram and Typical Application
V+
14
1
DETECTOR
BUF OUT
BUFFER
LEVEL
RMS
+
8
AVG CAP
C
2.2µF
AVG
5
VCA
SSM2166
10µF
C6
Rev. D | Page 9 of 20
1kΩ
+
IN
3
R
COMP
4
1kΩ
VCA
10µF (OPTIONAL)
+
C7
LEVEL DETECTOR
The SSM2166 incorporates a full-wave rectifier and true rms
level detector circuit whose averaging time constant is set by
an external capacitor connected to the AVG CAP pin (Pin 8).
For optimal low frequency operation of the level detector
down to 10 Hz, the value of the capacitor should be 2.2 μF.
Some experimentation with larger values for the AVG CAP
may be necessary to reduce the effects of excessive low frequency
ambient background noise. The value of the averaging capacitor
affects sound quality: too small a value for this capacitor may
cause a pumping effect for some signals, while too large a value
may result in slow response times to signal dynamics. Electrolytic
capacitors are recommended for lowest cost and should be in
the range of 2 μF to 47 μF. Capacitor values from 18 μF to 22 μF
have been found to be more appropriate in voice-band applications
where capacitors on the low end of the range seem more
appropriate for music program material.
The rms detector filter time constant is approximately given by
10 × C
controls both the steady-state averaging in the rms detector as
well as the release time for compression; that is, the time it takes
for the system gain to react when a large input is followed by
a small signal. The attack time, the time it takes for the gain to
be reduced when a small signal is followed by a large signal, is
controlled partly by the AVG CAP value but is mainly controlled by
internal circuitry that speeds up the attack for large level changes.
This limits overload time to less than 1 ms in most cases.
CONTROL
10
CIRCUIT
R
COMP
RATIO SET
VCA
AVG
milliseconds, where C
13
11
12
2
9
OUTPUT
GAIN ADJUST
NOISE GATE SET
ROTATION SET
POWER DOWN
R
GAIN
V
OUT
R
GATE
R
ROT PT
AVG
V+
is in μF. This time constant
SSM2166