LM185-2.5-N, LM285-2.5-N, LM385-2.5-N

SNVS743D – DECEMBER 1999 – REVISED MARCH 2013

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Calibration

Calibration

1.

1.

2.

Remove short, adjust R2 for correct reading in °F

2.

Remove short, adjust R2 for correct reading in centigrade

Figure 20. 0°C–100°C Thermomemter

Figure 21. 0°F–50°F Thermomemter

Adjustment Procedure

1.

Adjust TC ADJ pot until voltage across R1 equals Kelvin temperature multiplied by the thermocouple Seebeck

coefficient.

2.

Adjust zero ADJ pot until voltage across R2 equals the thermocouple Seebeck coefficient multiplied by 273.2.

Figure 22. Micropower Thermocouple Cold Junction Compensator

Seebeck

R1

R2

Voltage Across R1

Voltage Across R2

Coefficient

(

Ω)

(

Ω)

@25°C

(mV)

(mV)

J

52.3

523

1.24k

15.60

14.32

T

42.8

432

1k

12.77

11.78

K

40.8

412

953

Ω

12.17

11.17

S

6.4

63.4

150

Ω

1.908

1.766

(1)

Typical supply current 50

μA

8

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