LT1025_15 Datasheet, PDF (9/12 Pages) Linear Technology – Micropower Thermocouple Cold Junction Compensator

TYPICAL APPLICATIO S
Type S Thermocouple Amplifier with Ultralow Offset and Drift ^†
R2**
100Ω
R3
FULL-SCALE
909k
TRIM
1%
V⁺
V_IN
R,S _{– +}
LT1025
GND
R^{– VO}
TYPE S
R7
750k
R1
1k
1%
1µF
R6
12k
R4
1.37M
1%
R4
2.7k
0.1µF
15V
2_– 7
5
V⁺
LT1052
3₊
V^–
4
1
0.1µF
R5*
10k
OFFSET
TRIM
–15V
LT1009
2.5V
6
V_OUT
10mV/°C
8
800°C TO 1200°C
0.1µF
LT1025 • TA06
* TRIM R5 FOR V_OUT = 1.669V AT V_IN = 0.000mV (+INPUT OF AMPLIFIER GROUNDED)
** TRIM R2 FOR V_OUT = 9.998V AT T = 1000°C, OR FOR V_IN AT +INPUT OF AMPLIFIER = 9.585mV
† _{THIS AMPLIFIER HAS A DELIBERATE OFFSET TO ALLOW OUTPUT SLOPE (10mV/°C) TO BE SET}
INDEPENDENTLY FROM AN ARBITRARY HIGH TEMPERATURE CENTER POINT (1000°C). THIS IS
REQUIRED BECAUSE THE SLOPE OF TYPE “S” THERMOCOUPLES VARIES RAPIDLY WITH
TEMPERATURE, INCREASING FROM 6µV/°C AT 25°C to 11µV/°C AT 1000°C. NONLINEARITY LIMITS
ACCURACY TO ≈3°C OVER THE 800°C TO 1200°C RANGE EVEN WITH OFFSET CORRECTION
LT1025
1025fb
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