LINER LTKA01MH Thermocouple cold junction compensator and matched amplifier Datasheet

LTK001
Thermocouple Cold Junction
Compensator and
Matched Amplifier
thermocouple applications. It has low supply current to
minimize warmup drift, very low offset voltage (<35µV),
high gain, and extremely low input bias currents (<600pA)
to allow high impedance input filters to be used without
degrading offset voltage or drift.
FEATURES
■
■
■
■
■
■
0.75°C Initial Accuracy (A Version)
Extremely Low Warmup Drift
Preset Outputs for Type E, J, K, R, S, T
Single 5V to ± 20V Operation
480µA Typical Supply Current
Available in 8-Pin DIP Package
Matching of the kits is accomplished by separating the
compensators and amplifiers according to the polarity of
their initial (room temperature) errors. This eliminates the
need to sum the errors of the two components to find the
worst-case error.
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APPLICATIO S
■
The LTK001 has direct thermocouple outputs of
60.9µV/°C (E), 51.7µV/°C (J), 40.6µV/°C (K, T), and
5.95µV/°C (R, S). It also has a 10mV/°C output which can
be scaled to match any arbitrary thermocouple.
Thermocouple Cold Junction Compensation
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DESCRIPTIO
The LTK001 is a thermocouple amplifier supplied with a
matched cold junction compensator. By separating the
amplifier and compensator functions, the problem of
compensator temperature rise is virtually eliminated. The
compensator is a selected version of the LT®1025 cold
junction compensator. The amplifier, which is also available separately as LTKA0x has been specially selected for
For multiple thermocouple applications using one compensator, amplifiers may be ordered separately (LTKA0x),
still matched to the compensator.
, LTC and LT are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. For typical performance curves and
applications circuits consult the LT1025 data sheet.
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TYPICAL APPLICATIO
Type K 10mV/°C Thermometer
R2
100Ω
FULL-SCALE TRIM
R3**
255k
1%
C2
0.1µF
R1
1k
1%
V+
V+
–
LTKA0x
VIN
K
–
LT1025
GND
*
+
C1
0.1µF
+
VOUT
10mV/°C
V–
TYPE K
V0
R–
R4*
V–
–
*R4 ≤ V , R4 IS NOT REQUIRED (OPEN) FOR
30µA
LT1025 TEMPERATURES ≥ 0°C.
**SELECTED FOR 0°C–100°C RANGE
LTK001 TA01
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LTK001
W W
W
AXI U
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ABSOLUTE
RATI GS
(Note 1)
Amplifier (LTKA0x)
Supply Voltage (Total V + to V –) ............................... 40V
Differential Input Current (Note 2) ...................... ±10mA
Common Mode Input Voltage ............. Equal to Supplies
Output Short-Circuit Duration .......................... Indefinite
Compensator (LT1025)
Supply Voltage (VIN to Ground Pin) ......................... 36V
Output Voltage (Forced) ............................................ 5V
Output Short-Circuit Duration .......................... Indefinite
Both Devices
Operating Temperature Range
LTK001AMJ8, LTK001MJ8 (OBSOLETE)
......................................................... – 55°C to 125°C
LTK001ACN8, LTK001CN8 ...................... 0°C to 70°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature Range (Soldering, 10 sec.)...... 300°C
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U
W
PACKAGE/ORDER I FOR ATIO
TOP VIEW
E
60.9µV/°C 1
VIN 2
VO
10mV/°C 3
8
7
6
GND 4
TOP VIEW
VOS TRIM
TOP VIEW
5
J
51.7µV/°C
K,T
40.6µV/°C
R,S
6µV/°C
R–
COMMON
N8 PACKAGE
8-LEAD PDIP
COMPENSATOR
(LT1025)
TJMAX = 100°C, θJA = 130°C/W (N8)
VOS TRIM 1
8
VOS TRIM
–IN 2
7
V+
+IN 3
V– 4
6
OUT
5
OVER COMP
N8 PACKAGE
8-LEAD PDIP AMPLIFIER
(LTKA0x)
TJMAX = 100°C, θJA = 130°C/W
8
VOS
TRIM 1
–IN 2
–
+
7 V+
6 OUT
5 OVER COMP
+IN 3
4
V–
H PACKAGE
8-LEAD TO-5 METAL CAN
AMPLIFIER (LTKA0x)
TJMAX = 150°C, θJA = 150°C/W, θJC = 45°C/W
ORDER PART NUMBER
ORDER PART NUMBER
ORDER PART NUMBER
KIT
LTK001CN8
LTK001ACN8
AMPLIFIER ONLY
(Note A)
LTKA00CN8
LTKA01CN8
AMPLIFIER ONLY
(Note A)
LTKA00MH
LTKA01MH
J8 PACKAGE
8-LEAD CERDIP
COMPENSATOR
(LT1025)
TJMAX = 150°C, θJA = 100°C/W (J8)
LTK001MJ8
LTK001AMJ8
OBSOLETE PACKAGE
OBSOLETE PACKAGE
Consider the N8 Package for Alternate Source
Note A: The polarity of the amplifier is indicated by the 0 or 1 in the part
number. An LT1025 with a 0 identifier is properly matched with an LTKA00,
while an LT1025 with a 1 identifier should be used with an LTKA01.
Consult factory for parts specified with wider operating temperature ranges.
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LTK001
ELECTRICAL CHARACTERISTICS (Matched Amplifier and Compensator)
TA = 25°C, VS = ±15V (Amplifier), VS = 5V (Compensator)
PARAMETER
CONDITIONS
Total Temperature Error at 25°C
(Note 3)
MIN
Total Temperature Error at
Temperature Extremes (Note 9)
0°C ≤ TJ ≤ 70°C
0°C ≤ TJ ≤ 70°C
LTK001
TYP
MAX
UNITS
0.75
2.5
°C
0.75
2.5
°C
Type K, T
0.86
2.5
°C
5.0
5.0
°C
Type E
(Note 12)
0.05
0.09
°C/°C
Type J
0.06
0.09
°C/°C
Type K, T
0.07
0.10
°C/°C
Type R, S
0.28
0.32
°C/°C
Type E
2.0
5
Type J
2.1
5
°C
Type K, T
2.6
5.2
°C
(Note 12)
°C
16
16
°C
Type E
6
8.5
°C
Type J
6
8.5
°C
6.3
9
°C
30
30
°C
0.1
0.1
°C/V
900
µA
Type K, T
Type R, S
(Note 12)
Temperature Error Change with
Supply Voltage (Note 5)
Supply Current
MIN
Type J
Type R, S
– 55°C ≤ TJ ≤ 125°C
MAX
Type E
Type R, S
Slope Error (Notes 4 and 9)
LTK001A
TYP
480
900
480
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LTK001
ELECTRICAL CHARACTERISTICS (Compensator LT1025)
The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
VS = 5V unless otherwise noted.
PARAMETER
CONDITIONS
Temperature Error at 10mV/°C Output (Note 9)
TJ = 25°C, LTK001A
TJ = 25°C, LTK001
Full Temperature Span
Temperature Error at Individual Outputs (Note 10)
0.3
0.5
●
0.5
2.0
UNITS
°C
°C
See Curve on LT1025 Data Sheet
LTK001A: E, J, K, T
LTK001A: R, S
0.4
0.4
0.75
1.5
°C
°C
LTK001: E, J, K, T
LTK001: R, S
0.8
1.2
2.4
3.5
°C
°C
Full Temperature Span
Supply Current
COMPENSATOR (LT1025)
MIN
TYP
MAX
●
4V ≤ VIN ≤ 36V
80
0°C ≤ TJ ≤ 70°C
●
– 55°C ≤ TJ ≤ 125°C
●
Change in Supply Current
4V ≤ VIN ≤ 36V
Line Regulation (Note 11)
4V ≤ VIN ≤ 36V
10mV/°C Output
Load Regulation (Note 11)
0 ≤ IO ≤ 1mA
10mV/°C Output
Divider Impedance
E
J
K, T
R, S
See Curve on LT1025 Data Sheet
100
µA
150
µA
200
µA
0.01
0.05
µA/V
●
0.003
0.02
°C/V
●
0.04
0.2
°C
2.5
2.1
4.4
3.8
kΩ
kΩ
kΩ
kΩ
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LTK001
ELECTRICAL CHARACTERISTICS (Amplifier LTKA0x)
The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
VS = ±15V, VCM = 0V, TJ = 25°C unless otherwise noted.
PARAMETER
AMPLIFIER (LTKA0x)
MIN
TYP
MAX
CONDITIONS
Input Offset Voltage
UNITS
10
35
µV
Input 0ffset Voltage Drift with Temperature
(Note 6)
●
0.3
1.5
µV/°C
Input Bias Current
0°C ≤ TA ≤ 70°C
– 55°C ≤ TA ≤ 125°C
●
●
± 200
± 300
± 600
± 1500
Input Bias Current Drift with Temperature
(Note 6)
1
5
lnput 0ffset Current
0°C ≤ TA ≤ 70°C
– 55°C ≤ TA ≤ 125°C
●
●
± 100
± 200
± 500
± 700
lnput Offset Current Drift with Temperature
(Note 6)
●
0.6
4
Large Signal Voltage Gain
RL = 10kΩ
●
400
2000
V/mV
Common Mode Rejection Ratio
VCM = ± 13.5V
●
106
130
dB
Power Supply Rejection Ratio
± 2.5V ≤ VS ≤ ± 20V (Note 5)
●
106
125
dB
Common Mode Input Voltage Range
Notes 6, 7
Above
V–
0.75
Referred to Supplies
Supply Voltage Range
Total V + to V – Voltage
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The inputs of the LTKA0x amplifier are clamped with diodes, so a
differential voltage rating does not apply.
Note 3: Total temperature error is the overall error at 25°C taking into
account the offset of the amplifier, the offset at the compensator 10mV/°C
output, and the error in the compensator divider network. Warmup drift is
not included.
Note 4: Slope error is the increase in total temperature error as ambient
temperature is increased. It is guaranteed by design and by other tests,
but is not tested directly.
Note 5: This is a worst-case limit assuming that any or all supply voltages
change.
Note 6: Guaranteed, but not tested.
Note 7: By referring common mode range to the supplies, the range
referred to ground can be quickly calculated for any given supply voltage.
With a single 5V supply, for instance, which has a worst-case low value of
4.7V, the upper common mode limit is 4.7V – 1V = 3.7V. The lower
common mode limit is 0V + 0.75V = 0.75V. With ±15V supplies, the limits
would be 14V and –14.25V, respectively. Common mode range has a
temperature sensitivity of ≈ 2mV/°C.
Note 8: Absolute output voltage swing is calculated by subtracting the
given limits from actual supply voltage. These limits indicate the point
where offset voltage has changed suddenly by 5µV.
pA
pA
pA/°C
1.0
V
IOUT = 0.1mA
0.8
V
IOUT = 1mA
1.1
V
●
Supply Current
pA/°C
V
Below V +
Output Voltage Swing (Notes 6, 8)
pA
pA
●
400
4.5
800
µA
40
V
Note 9: Temperature error is defined as the deviation from the following
formula:
VOUT = α(T) + αß(T – 25°C)2
α = Typical thermocouple Seebeck coefficient as follows,
E = 60.9µV/°C, J = 51.7µV/°C, K, T = 40.6µV/°C, R, S = 5.95µV/°C.
α = 10mV/°C at the 10mV output.
ß = Nonlinearity coefficient built into the LT1025 to help compensate
for the nonlinearities of thermocouples. ß = 5.5 x 10 –4, generating
0.34°C bow for 25°C temperature change, and 1.36°C bow for 50°C
change.
Note 10: Temperature error at the individual outputs is the sum of the
10mV/°C output error plus the resistor divider error.
Note 11: Line and load regulation do not take into account the effects of
self-heating. Output changes due to self-heating can be calculated as
follows:
∆VOUT (Line) = ∆VIN(Iq + Iload)(150°C/W)
∆VOUT (Load) = (∆Iload)(VIN)(150°C/W)
= LT1025 supply current
Load regulation is 30µA ≤ IO ≤ 1mA for TA ≤ 0°C.
Note 12: Larger errors with type R and S thermocouples are due mostly to
35µV offset of the amplifier. This error can be reduced to 5µV max with the
LTC®1050 or LTC1052 operational amplifiers.
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LTK001
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PACKAGE DESCRIPTIO
H Package
8-Lead TO-5 Metal Can (.200 Inch PCD)
(Reference LTC DWG # 05-08-1320)
.335 – .370
(8.509 – 9.398)
DIA
.305 – .335
(7.747 – 8.509)
.040
(1.016)
MAX
.050
(1.270)
MAX
SEATING
PLANE
.165 – .185
(4.191 – 4.699)
GAUGE
PLANE
.010 – .045*
(0.254 – 1.143)
REFERENCE
PLANE
.500 – .750
(12.700 – 19.050)
.016 – .021**
(0.406 – 0.533)
.027 – .045
(0.686 – 1.143)
45°
PIN 1
.028 – .034
(0.711 – 0.864)
.200
(5.080)
TYP
.110 – .160
(2.794 – 4.064)
INSULATING
STANDOFF
*LEAD DIAMETER IS UNCONTROLLED BETWEEN THE REFERENCE PLANE
AND THE SEATING PLANE
.016 – .024
**FOR SOLDER DIP LEAD FINISH, LEAD DIAMETER IS
(0.406 – 0.610) H8(TO-5) 0.200 PCD 0204
OBSOLETE PACKAGE
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LTK001
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PACKAGE DESCRIPTIO
J8 Package
8-Lead CERDIP (Narrow .300 Inch, Hermetic)
(Reference LTC DWG # 05-08-1110)
CORNER LEADS OPTION
(4 PLCS)
.023 – .045
(0.584 – 1.143)
HALF LEAD
OPTION
.045 – .068
(1.143 – 1.650)
FULL LEAD
OPTION
.005
(0.127)
MIN
.405
(10.287)
MAX
8
7
6
5
.025
(0.635)
RAD TYP
.220 – .310
(5.588 – 7.874)
1
.300 BSC
(7.62 BSC)
2
3
4
.200
(5.080)
MAX
.015 – .060
(0.381 – 1.524)
.008 – .018
(0.203 – 0.457)
0° – 15°
NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE
OR TIN PLATE LEADS
.045 – .065
(1.143 – 1.651)
.014 – .026
(0.360 – 0.660)
.100
(2.54)
BSC
.125
3.175
MIN
J8 0801
OBSOLETE PACKAGE
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Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LTK001
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PACKAGE DESCRIPTIO
N8 Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
.400*
(10.160)
MAX
8
7
6
5
1
2
3
4
.255 ± .015*
(6.477 ± 0.381)
.300 – .325
(7.620 – 8.255)
.008 – .015
(0.203 – 0.381)
+.035
.325 –.015
(
8.255
+0.889
–0.381
)
.045 – .065
(1.143 – 1.651)
.130 ± .005
(3.302 ± 0.127)
.065
(1.651)
TYP
.100
(2.54)
BSC
.120
(3.048) .020
MIN
(0.508)
MIN
.018 ± .003
(0.457 ± 0.076)
N8 1002
NOTE:
1. DIMENSIONS ARE
INCHES
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1012
Picoamp Input Current Amplifier
VOS = 120µV MAX, IOS = 280pA MAX
LT1025
Thermocouple Cold Junction Comparator
Micropower, 0.5°C Initial Accuracy
LTC1050
Zero Drift Amplifier
VOS = 5µV MAX, AVOL = 1V/µV MAX
LTC2050
SOT-23 Zero Drift Amplifier
VOS = 3µV MAX
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Linear Technology Corporation
LT/LT 0305 REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com
© LINEAR TECHNOLOGY CORPORATION 2001
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