OPA2277-EP Datasheet, PDF (12/21 Pages) Texas Instruments – OPA2277-EP High-Precision, Low-Noise Operational Amplifier

OPA2277-EP
SBOS700 – DECEMBER 2014
9 Application and Implementation
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NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
The OPA2277 is unity-gain stable and free from unexpected output phase reversal, making it easy to use in a
wide range of applications. Applications with noisy or high-impedance power supplies may require decoupling
capacitors close to the device pins. In most cases, 0.1-μF capacitors are adequate.
9.2 Typical Application
I_REG ∼ 1mA
5V
Type J
V+
1/2
OPA2277
R_F
10kΩ
R
412Ω ^RF
10kΩ
1kΩ
1/2
OPA2277
50Ω
V–
25Ω
R_CM = 1250Ω
12
V_LIN ¹
13 _VI+N ^IR1
4
R_G
14
I_R2
11
V_REG
10
V+
R_G
1250Ω
XTR105
B9
3 _RG
2 ^VI–N
I_RET
6
E
8
I_O
7
I_O
=
4mA +
(V_I+N
– V_I–N)
40
R_G
0.01μF
(G = 1 + ^2RF = 50)
R
Figure 21. Thermocouple Low-Offset, Low-Drift Loop Measurement With Diode Cold Junction
Compensation
9.2.1 Design Requirements
For the thermocouple low-offset, low-drift loop measurement with diode cold junction compensation (see
Figure 21), Table 1 lists the design parameters needed with gain = 50.
G 1  ^2RF 50
R
(1)
Table 1. Design Parameters
DESIGN PARAMETER
R_F
R
EXAMPLE VALUE
10 kΩ
412 Ω
12
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