OP27A Datasheet, PDF (20/21 Pages) Texas Instruments – LOW-NOISE HIGH-SPEED PRECISION OPERATIONAL AMPLIFIERS

OP27A, OP27C, OP27E, OP27G
OP37A, OP37C, OP37E, OP37G
LOW-NOISE HIGH-SPEED PRECISION OPERATIONAL AMPLIFIERS
SLOS100B – FEBRUARY 1989 – REVISED AUGUST 1994
APPLICATION INFORMATION
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
+
–
AVD = 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 40. Low-Noise, Multiplexed Thermocouple Amplifier and 0.1-Hz To 10-Hz
Peak-to-Peak Noise Voltage
2–20
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