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参数资料
| 型号： | SSM-2122 |
| 厂商： | Analog Devices, Inc. |
| 英文描述： | Dynamic Range Processors/Dual VCA |
| 中文描述： | 动态范围处理器/双壳抗原 |
| 文件页数： | 5/12页 |
| 文件大小： | 371K |
| 代理商： | SSM-2122 |
SSM2120/SSM2122
REV. C
–5–
The decay rates are linear ramps that are dependent on the
current out of the LOG AV pin (set by R
REF
) and the value of
C
AV
. The integration or decay time of the circuit is derived from
the formula:
Decrementation Rate (in dB/s) =
I
REF
×
333
C
AV
Table I. Settling Time (t
S
) for C
AV
= 10
m
F. t
S
= t
S
(C
AV
= 10
m
F)
5 dB
3 dB
2 dB
1 dB
10 dB Step
20 dB Step
30 dB Step
40 dB Step
50 dB Step
60 dB Step
11.28 ms
16.65
18.15
18.61
21.46
26.83
28.33
27.79
30.19
35.56
37.06
37.52
(+144
μ
s)
(+46
μ
s)
46.09
51.46
52.96
53.42
APPLICATIONS
The following applications for the SSM2120 use both the VCAs
and level detectors in conjunction to assimilate a variety of
functions.
The first section describes the arrangement of the threshold
control in each control circuit configuration. These control
circuits form the foundation for the applications to follow which
include the downward expander, compressor/limiter and
compandor.
THRESHOLD CONTROL
Figure 6a shows the control circuit for a typical downward
expander while Figure 6b shows a typical control curve. Here,
the threshold potentiometer adjusts V
T
to provide a negative
unipolar control output. This is typically used in noise gate,
downward expander, and dynamic filter applications. This
potentiometer is used in all applications to control the signal
level versus control voltage characteristics.
10
0%
100
90
1s
2V
Figure 4. Detector Output
10
0%
100
90
2V
50ms
Figure 5. Overlayed Detector Output
DYNAMIC ATTACK AND DECAY RATES
Figure 5 shows the output levels overlayed using a storage
scope. The attack rate is determined by the step size and the
value of C
AV
. The attack time to final value is a function of the
step size increase. Table I shows the values of total settling
times to within 5 dB, 3 dB, 2 dB and 1 dB of final value with
C
AV
= 10
μ
F. When step sizes exceed 40 dB, the increase in
settling time for larger steps is negligible. To calculate the attack
time to final value for any value of C
AV
, simply multiply the
value in the chart by C
AV
/10
μ
F.
V
IN
– dB
+
–
*LOWER LIMIT CAN BE FIXED
BY CONNECTING A RESISTOR
R
LL
FROM REC
IN
TO GROUND
THRESHOLD
V
C
*
2V
|I
IN
|
V+
V–
CON
OUT
REC
IN
39k
200
R
CON
TO +V
C
R
IN
MONO
OR R
C
AV
R
LL
R
T
THRESHOLD
CONTROL
LOG AV
R
IN
L
MONO – R
IN
= 10k
STEREO – R
IN
= 20k
V–
1.5M
1k
V–
V
T
a. Control Circuit b. Typical Downward Expander
Control Curve
Figure 6. Noise Gate/Downward Expander Control Circuit and Typical Response
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相关代理商/技术参数 |
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|---|---|
| SSM2122P | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Amplifier. Other |
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| SSM2125A0011P | 制造商:Analog Devices 功能描述: |
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