LM385Z-1.2 datasheet(7/11 Pages) NSC

7 / 11 page

Typical Applications (Continued)

METER THERMOMETERS

0˚C−100˚C Thermometer

00551828

Calibration

1. Short LM385-1.2, adjust R3 for IOUT= temp at 1µA/˚K

2. Remove short, adjust R2 for correct reading in centigrade

†IQ at 1.3V.500µA

IQ at 1.6V.2.4mA

Lower Power Thermometer

00551829

*2N3638 or 2N2907 select for inverse HFE . 5

†Select for operation at 1.3V

‡IQ . 600µA to 900µA

0˚F−50˚F Thermometer

00551830

Calibration

1. Short LM385-1.2, adjust R3 for IOUT= temp at 1.8µA/˚K

2. Remove short, adjust R2 for correct reading in ˚F

Micropower Thermocouple Cold Junction

Compensator

00551831

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.

Thermocouple

Seebeck

R1 R2

Voltage

Type

Coefficient (

Ω)(Ω) Across

Across

(µV/˚C)

@ 25˚C

(mV)

52.3

5231.24k

15.60

14.32

42.8

432 1k

12.77

11.78

40.8

412953

Ω

12.17

11.17

6.4

63.4150

Ω

1.908

1.766

Typical supply current 50µA

LM385Z-1.2 Datasheet(PDF) 7 Page - National Semiconductor (TI)

LM385Z-1.2 Datasheet(HTML) 7 Page - National Semiconductor (TI)

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