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
2
4
6
8
10
t – Time – seconds
Type S Thermocouples
5.4 µV/°C at 0°C
+
#1
Cold-Junction
Circuitry
–
+
To Gate
Drive
–
+
A
VD
= 10,000
#2
–
+
Output
100 kΩ
OP27
–
Typical
Multiplexing
0.05 µF
FET Switches
+
#24
–
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
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
POST OFFICE BOX 1443 • HOUSTON, TEXAS 77251–1443
TI [ TEXAS INSTRUMENTS ]
