Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.COM

X  

LT1025 Datasheet(PDF) 6 Page - Linear Technology

Part # LT1025
Description  Micropower Thermocouple Cold Junction Compensator
Download  12 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  LINER [Linear Technology]
Direct Link  http://www.linear.com
Logo LINER - Linear Technology

LT1025 Datasheet(HTML) 6 Page - Linear Technology

Back Button LT1025_15 Datasheet HTML 2Page - Linear Technology LT1025_15 Datasheet HTML 3Page - Linear Technology LT1025_15 Datasheet HTML 4Page - Linear Technology LT1025_15 Datasheet HTML 5Page - Linear Technology LT1025_15 Datasheet HTML 6Page - Linear Technology LT1025_15 Datasheet HTML 7Page - Linear Technology LT1025_15 Datasheet HTML 8Page - Linear Technology LT1025_15 Datasheet HTML 9Page - Linear Technology LT1025_15 Datasheet HTML 10Page - Linear Technology Next Button
Zoom Inzoom in Zoom Outzoom out
 6 / 12 page
background image
6
LT1025
1025fb
Figure 4. Thermocouple Nonlinearity, 0
°C to 400°C
Figure 5. Offset Curve Fitting
In many situations, thermocouples are used in high noise
environments, and some sort of input filter is required.
(See discussion of input filters). To reject 60Hz pick-up
with reasonable capacitor values, input resistors in the
10k-100k range are needed. Under these conditions, bias
current for the amplifier needs to be less than 1nA to avoid
offset and drift effects.
To avoid gain error, high open loop gain is necessary for
single-stagethermocoupleamplifierswith10mV/
°Corhigher
outputs. A type K amplifier, for instance, with 100mV/
°C
output, needs a
closed loop gain of
≈2,500. An ordinary op
amp with a minimum open loop of 50,000 would have an
initial gain error of (2,500)/(50,000) = 5%! Although closed
loop gain is commonly trimmed, temperature drift of open
loop gain will have a very deleterious effect on output
accuracy. Minimum suggested open loop gain for type E, J,
K, and T thermocouples is 250,000. This gain is adequate for
type R and S if output scaling is 10mV/
°C or less.
Suggested Amplifier Types
SUPPLY VOLTAGE
THERMOCOUPLE
±15V
±5V
SINGLE SUPPLY
E, J, K, T
LTKA0x
LTKA0x
LTC1050
LT1012
LT1012
LTC1052
LT1001
LT1001
LT1006
LTC1050
LTC1052
LT1006
R, S
LTKA0x
LTC1050
LTC1050
LT1012
LTC1052
LTC1052
LTKA0x
LT1006
Thermocouple Nonlinearities
Thermocouples are linear over relatively limited temperature
spans if accuracies of better than 2
°C are needed. The graph
in Figure 4 shows thermocouple nonlinearity for the
temperature range of 0
°C to 400°C. Nonlinearities can be
dealtwithinhardwarebyusingoffsets,breakpoints,orpower
series generators. Software solutions include look-up tables,
power series expansions, and piece-wise approximations.
For tables and power series coefficients, the reader is referred
to the ASTM Publication 470A.
Hardware correction for nonlinearity can be as simple as an
offset term. This is shown in Figure 5. The thermocouple
shown in the figure has an increasing slope (
α) with
temperature. The temperature range of interest is between TL
and TH, with a calibration point at TM. If a simple amplifier is
used and calibrated at TM, the output will be very high at TL
and very low at TH. Adding the proper offset term and
calibrating at T1/6 or T5/6 can significantly reduce errors. The
technique is as follows:
1. Calculate amplifier gain:
G = (SF) (TH – TL)/(VH – VL)
SF = Output scale factor, e.g., 10mV/
°C
VH = Thermocouple output at TH
VL = Thermocouple output at TL
2. Use precision resistors to set gain or calibrate gain by
introducing a precision “delta” input voltage and trimming
for proper “delta” output.
APPLICATIO S I FOR ATIO
TEMPERATURE (
°C)
0
20
15
12.5
10
5
100
200
250
LT1025 • G04
17.5
2.5
0
7.5
8
6
5
4
2
7
1
0
3
50
150
300 350
400
K
→SCALE
J
→SCALE
SCALE
←E
SCALE
←T
TEMPERATURE (
°C)
0
VL
VH
LT1025 • G05
T1/6
TH
TL
TM
T5/6
THERMOCOUPLE
SIMPLE AMPLIFIER
OFFSET AMPLIFIER
ERROR AFTER OFFSETTING
ERROR BEFORE OFFSETTING


Similar Part No. - LT1025_15

ManufacturerPart #DatasheetDescription
logo
Linear Technology
LT1025AC LINER-LT1025AC Datasheet
656Kb / 8P
   Micropower Thermocouple Cold Junction Compensator
LT1025ACJ8 LINER-LT1025ACJ8 Datasheet
182Kb / 12P
   Micropower Thermocouple Cold Junction Compensator
LT1025ACN8 LINER-LT1025ACN8 Datasheet
656Kb / 8P
   Micropower Thermocouple Cold Junction Compensator
LT1025ACN8 LINER-LT1025ACN8 Datasheet
193Kb / 12P
   Micropower Thermocouple Cold Junction Compensator
LT1025ACN8 LINER-LT1025ACN8 Datasheet
182Kb / 12P
   Micropower Thermocouple Cold Junction Compensator
More results

Similar Description - LT1025_15

ManufacturerPart #DatasheetDescription
logo
Analog Devices
AC1226 AD-AC1226_15 Datasheet
395Kb / 4P
   MICROPOWER THERMOCOUPLE COLD JUNCTION COMPENSATOR
REV. A
AC1226 AD-AC1226 Datasheet
374Kb / 4P
   Micropower Thermocouple Cold Junction Compensator
logo
Linear Technology
LT1025 LINER-LT1025_03 Datasheet
193Kb / 12P
   Micropower Thermocouple Cold Junction Compensator
LT1025ACJ8 LINER-LT1025ACJ8 Datasheet
182Kb / 12P
   Micropower Thermocouple Cold Junction Compensator
LT1025 LINER-LT1025 Datasheet
656Kb / 8P
   Micropower Thermocouple Cold Junction Compensator
logo
List of Unclassifed Man...
2B56 ETC1-2B56 Datasheet
37Kb / 1P
   High Accuracy, Thermocouple Cold Junction Compensator
logo
Intronics Power, Inc.
2B56 INTRONICS-2B56 Datasheet
1Mb / 4P
   High Accuracy, Thermocouple Cold Junction Compensator
logo
Linear Technology
LTK001 LINER-LTK001_09 Datasheet
105Kb / 8P
   Thermocouple Cold Junction Compensator and Matched Amplifier
LTK001 LINER-LTK001 Datasheet
286Kb / 4P
   Thermocouple Cold Junction Compensator and Matched Amplifier
LTK001 LINER-LTK001_15 Datasheet
110Kb / 8P
   Thermocouple Cold Junction Compensator and Matched Amplifier
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com