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ManualsBrandsTEXAS INSTRUMENTS ManualsLinear ICsLinear IC - Op-amp Variable gain SOIC 14
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50W
R
F
50W
V
G
V
IN
50W
Source
R
G
50W
Load
V
OUT
R
1
R
2
R
3
+V
IN
-V
IN
R
G-
R
G+
VCA820
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............................................................................................................................................ SBOS395C –OCTOBER 2007–REVISED OCTOBER 2009
Table 2. SO-14 and MSOP-10 R
F
and R
G
OPERATING SUGGESTIONS
Configurations
Operating the VCA820 optimally for a specific
G = 2 G = 10 G = 100
application requires trade-offs between bandwidth,
R
F
1.33kΩ 1kΩ 845Ω
input dynamic range and the maximum input voltage,
the maximum gain of operation and gain, output
R
G
1.33kΩ 200Ω 16.9Ω
dynamic range and the maximum input voltage, the
There are no differences between the packages in
package used, loading, and layout and bypass
the recommended values for the gain and feedback
recommendations. The Typical Characteristics have
resistors. However, the bandwidth for the
been defined to cover as much ground as possible to
VCA820IDGS (MSOP-10 package) is lower than the
describe the VCA820 operation. There are four
bandwidth for the VCA820ID (SO-14 package). This
sections in the Typical Characteristics:
difference is true for all gains, but especially true for
• V
S
= ±5V DC Parameters and V
S
= ±5V DC and
gains greater than 5V/V, as can be seen in Figure 85
Power-Supply Parameters, which include dc
and Figure 86. Note that the scale must be changed
operation and the intrinsic limitation of a VCA820
to a linear scale to view the details.
design
• V
S
= ±5V, A
VMAX
= 6dB Gain of 6dB Operation
• V
S
= ±5V, A
VMAX
= 20dB Gain of 20dB Operation
• V
S
= ±5V, A
VMAX
= 40dB Gain of 40dB Operation
Where the Typical Characteristics describe the actual
performance that can be achieved by using the
amplifier properly, the following sections describe in
detail the trade-offs needed to achieve this level of
performance.
PACKAGE CONSIDERATIONS
The VCA820 is available in both SO-14 and
MSOP-10 packages. Each package has, for the
different gains used in the typical characteristics,
different values of R
F
and R
G
in order to achieve the
same performance detailed in the Electrical
Figure 85. SO-14 Recommended R
F
and R
G
Characteristics table.
versus A
VMAX
Figure 84 shows a test gain circuit for the VCA820.
Table 2 lists the recommended configuration for the
SO-14 and MSOP-10 package.
Figure 86. MSOP-10 Recommended R
F
and R
G
versus A
VMAX
Figure 84. Test Circuit
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