OP27GU Datasheet, PDF (18/22 Pages) Texas Instruments – LOW-NOISE HIGH-SPEED PRECISION OPERATIONAL AMPLIFIERS

OP27A, OP27C
LOW-NOISE HIGH-SPEED PRECISION OPERATIONAL-AMPLIFIER
SLOS100E − FEBRUARY 1989 − REVISED FEBRUARY 2010
APPLICATION INFORMATION
unity gain buffer applications (continued)
120
100
80
60
40
20
0
0
Type S Thermocouples
5.4 μV/°C at 0°C
+
#1
−
To Gate
Drive
+
#2
−
Typical
Multiplexing
+
FET Switches
#24
−
2
4
6
8
10
t − Time − seconds
Cold-Junction
Circuitry
+
−
A_VD = 10,000
+
OP27
−
0.05 μF
Output
100 kΩ
High-Quality
Single-Point Ground
10 Ω
NOTE A: If 24 channels are multiplexed per second and the output is required to settle to 0.1 % accuracy, the amplifier’s bandwidth cannot be
limited to less than 30 Hz. The peak-to-peak noise contribution of the OP27 will still be only 0.11 μV, which is equivalent to an error
of only 0.02°C.
Figure 32. Low-Noise, Multiplexed Thermocouple Amplifier and
0.1-Hz to 10-Hz Peak-to-Peak Noise Voltage
18
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