Datasheet

7
LT1025
1025fb
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.
APPLICATIO S I FOR ATIO
WUUU
TYPICAL APPLICATIO S
U
–
–
+
+
4
6
7
2
3
–15V
15V
–15V
–10mV/°C
15V
3k
300k
GND R
–
K
TYPE K
C1
0.1µF
C2
1µF
V
IN
V
O
V
OUT
LT1025
LTKA0x
††
††
OR EQUIVALENT. SEE “AMPLIFIER CONSIDERATIONS”
Eliminating Amplifier Feedback Resistors
(Output Goes Negative with Increasing Temperature)
Type K Thermometer with Grounded Thermocouple
–15V
10mV/°C
V
OUT
V
+
V
–
V
–
V
–
GND R
–
LT1025
–
+
V
+
R5
10k
R1
1k
1%
R6
9.1k
R4*
470k
R3
255k
1%
R2
100Ω
TYPE K
0.1µF
C2
1µF
*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”
V
IN
V
O
IF OUTPUT MUST SINK CURRENT, R4
LTKA0x
††