LT1025ACJ8 Datasheet, PDF (7/12 Pages) Linear Technology – Micropower Thermocouple Cold Junction Compensator

LT1025
APPLICATIO S I FOR ATIO
3. Calibrate output by adding in a true offset term which
does not affect gain (by summing, etc.). Calibration may
be done at any temperature either by immersing the
thermocouple in a calibrated bath or by substituting a
precision input voltage. The method which tends to
minimize worst-case error over the whole T_L to T_H range
is to calibrate at 1/6 or 5/6 of span. This may be modified
if best accuracy is desired at one particular point.
Breakpoint correction for nonlinearity is more compli-
cated than a simple offset, but a single breakpoint com-
bined with offset will reduce errors typically by 4:1 over a
simple offset technique.
TYPICAL APPLICATIO S
Eliminating Amplifier Feedback Resistors
(Output Goes Negative with Increasing Temperature)
15V
V_IN
3k
+–
C2
1µF
TYPE K
C1
0.1µF
15V
2_– 7
LTKA0x^††
3₊
4
–15V
LT1025
K
GND
R^–VO
300k
–15V
6
V_OUT
–10mV/°C
†† _{OR EQUIVALENT. SEE “AMPLIFIER CONSIDERATIONS”}
Type K Thermometer with Grounded Thermocouple
R3
R2
255k
100Ω
1%
R1
1k
1%
R5
10k
C2
1µF
TYPE K
R6
9.1k _0.1µF
V⁺
–
LTKA0x^††
+
V^–
V⁺
V_{IN VO}
LT1025
GND R^–
V_OUT
10mV/°C
R4*
470k
V^–
–15V
*R4 ≤ ^V– IF OUTPUT MUST SINK CURRENT, R4
30µA
MUST BE DECREASED APPROPRIATELY. R4 IS NOT
REQUIRED (OPEN) FOR LT1025 TEMPERATURES ≥ 0°C
WHEN SOURCING CURRENT ONLY
†† _{OR EQUIVALENT. SEE “AMPLIFIER CONSIDERATIONS”}
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