1

LT1025

1025fb

DESCRIPTIO

APPLICATIO S

s

80

µA Supply Current

s

4V to 36V Operation

s

0.5

°C Initial Accuracy (A Version)

s

Compatible with Standard Thermocouples

(E, J, K, R, S, T)

s

Auxiliary 10mV/

°C Output

s

Available in 8-Lead PDIP and SO Packages

s

Thermocouple Cold Junction Compensator

s

Centigrade Thermometer

s

Temperature Compensation Network

Micropower Thermocouple

Cold Junction Compensator

Type K 10mV/

°C Thermometer

The LT

compensator for use with type E, J, K, R, S, and T

thermocouples. It utilizes wafer level and post-package

trimming to achieve 0.5

°C initial accuracy. Special curvature

correction circuitry is used to match the “bow” found in all

thermocouples so that accurate cold junction compensation

is maintained over a wider temperature range.

TheLT1025willoperatewithasupplyvoltagefrom4Vto36V.

Typical supply current is 80

µA, resulting in less than 0.1°C

internal temperature rise for supply voltages under 10V.

A 10mV/

°C output is available at low impedance, in addition

to the direct thermocouple voltages of 60.9

µV/°C (E),

51.7

µV/°C (J), 40.3µV/°C (K, T) and 5.95µV/°C (R, S). All

outputs are essentially independent of power supply voltage.

A special kit is available (LTK001) which contains an LT1025

and a custom tailored thermocouple amplifier. The amplifier

and compensator are matched to allow a much tighter specifi-

cation of temperature error than would be obtained by adding

the compensator and amplifier errors on a worst-case basis.

The amplifier from this kit is available separately as LTKA0x.

The LT1025 is available in either an 8-pin PDIP or 8-pin SO

package for temperatures between 0

°C and 70°C.

–

–

+

BOW*

CORRECTION

VOLTAGE

BUFFER

GND

E 60.9

µV/°C

R– COMMON

J 51.7

µV/°C

K,T 40.6

µV/°C

R, S 6

µV/°C

10mV/

°C

TEMPERATURE

SENSOR

*CORRECTS FOR BOW

IN

IN PROBE (HOT JUNCTION)

LT1025 • BD01

+

–

LTKA0x

††

TYPE K

R4*

R1

1k

1%

C2

0.1

µF

C1

0.1

µF

–+

R2

100

Ω

FULL-SCALE TRIM

10mV/

°C

R3**

255k

1%

30

µA

K

LT1025

*R4

≤

, R4 IS NOT REQUIRED

(OPEN) FOR LT1025 TEMPERATURES

≥ 0°C

**SELECTED FOR 0

°C TO 100°C RANGE

“AMPLIFIER CONSIDERATIONS”

LT1025 • TA01

FEATURES

, LTC and LT are registered trademarks of Linear Technology Corporation.

BLOCK DIAGRA

TYPICAL APPLICATIO