Datasheet

9
LT1025
1025fb
TYPICAL APPLICATIO S
U
Type S Thermocouple Amplifier with Ultralow Offset and Drift
†
+
–
* 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
V
+
V
+
V
–
TYPE S
R7
750k
R6
12k
–15V
LT1009
2.5V
R4
1.37M
1%
R1
1k
1%
R2**
100Ω
FULL-SCALE
TRIM
R3
909k
1%
0.1µF 0.1µF
1
4
8
6
7
3
5
2
R5*
10k
OFFSET
TRIM
R4
2.7k
1µF
0.1µF
15V
V
OUT
10mV/°C
800°C TO 1200°C
V
IN
V
O
LT1025
LT1052
GND R
–
R,S
–+
LT1025 • TA06