SSM2000 查看數據表（PDF） - Analog Devices
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SSM2000 Datasheet PDF : 16 Pages
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SSM2000
APPLICATIONS
This applications example (Figure 4) demonstrates some of the
additional functions that can be easily implemented through use
of the VCA Control Port (Pin 7). These functions can be selected
to operate simultaneously with the basic HUSH noise reduction
function. The VCA detector output provides a signal which can
be further processed using one quad op amp (OP482) to provide
these various additional useful functions.
The circuit shown in the figure below achieves: (1) Compres-
sion, (2) Volume Leveling, (3) DC Volume Adjustment.
C1
JA1
6.8µF
RCA
1
24
LEFT IN
C2
JA2
6.8µF
2
23
RCA
RIGHT IN
3
22
C3
0.001µF
4
21
SSM2000
+5V 5
20
SW1-F
SIDE CHAIN
OPEN = OUT
6
19
CLOSED = IN
7
18
C4
0.0022µF
8
17
R1
1kΩ
C5
0.022µF
9
C7
16
2.2µF
10
15
R2
510Ω
C6
0.022µF
10%
C8
1µF
11
14
C10
0.001µF
JA3
RCA
LEFT OUT
JA4
RCA
RIGHT OUT
–5V
+5V
SW1-C
MUTE
NC
R3
3kΩ
OPEN = MUTE
CLOSED = OFF
C11
0.22µF
+5V
R4
3kΩ
SW1-B
BYPASS
OPEN = BYPASS
CLOSED = HUSH
12
13 NC
C9
3.3µF
SW1-A
OPEN = COMP
CLOSED = LEVEL
R9
7.5kΩ
U1-A
3 OP482
R16
1
1.5MΩ 2
+5V
LEVEL
THRESHOLD
R7, 10kΩ
PT10V
R8
20kΩ
R10
5.1kΩ
1N4148
–5V
R11
12kΩ
SW1-D
OPEN = LEVEL
CLOSED = COMP
SW1-E
OPEN = LEVEL
CLOSED = COMP
R15
10MΩ
–5V
R12
20kΩ
13
14
12
U1-D
OP482
R13
20kΩ
R14
100kΩ
C12
1µF NON-POLARIZED
10% POLY, 63V
R18
30kΩ
R19
20kΩ
D2
1N4148
–5V
VOLUME
CONTROL
VR1, 10kΩ
LINEAR
9
R17
8
20kΩ
6
10
U1-C
OP482
7
5
U1-B
OP482
SIMPLIFIED THEORY OF OPERATION
The input audio signals are processed to extract information
concerning the frequency distribution and amplitude of both
the desired signals and the undesired noise. Left and right au-
dio signals are passed through voltage controlled (low-pass) fil-
ter, and then through a voltage controlled amplifiers. Both the
filters and amplifiers are low distortion, and add negligible noise
of their own. The VCF has a user-definable cutoff range that is
usually set from 1 kHz to 35 kHz. It can be set to cover other
ranges as required by the application. The VCA can be adjusted
from a loss to a gain, adding to the SSM2000’s versatility. In
accordance with proprietary patented algorithms, control sig-
nals are derived and applied to both the VCF and VCA, result-
ing in up to 25 dB noise suppression with the minimum loss of
desired signals.
VOLTAGE
VOLTAGE
RIN
CONTROLLED
CONTROLLED
FILTER
AMPLIFIER
ROUT
VOLTAGE
VOLTAGE
LIN
CONTROLLED
CONTROLLED
FILTER
AMPLIFIER
LOUT
DEFEAT
MUTE
LOGIC
INTERFACE
LOGIC
INTERFACE
EXTERNAL VCA
CONTROL PORT
DEFAULT
THRESHOLD
AUTO THRESHOLD
NEGATIVE PEAK
DETECTOR
DIFFERENCE
AMPLIFIER
HIGH-PASS
FILTER
PEAK
DETECTOR
PEAK
DETECTOR
DIFFERENCE
AMPLIFIER
Figure 5. SSM2000 System Block Diagram
Figure 4. Typical Dual Supply Application and Test Circuit
–4–
REV. 0
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