LM185-25 National Semiconductor, LM185-25 Datasheet - Page 8

• Manufacturer Part Number: LM185-25
• Description: Micropower Voltage Reference Diode
• Manufacturer: National Semiconductor

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LM385-2.5 Applications
METER THERMOMETERS
Calibration
1. Short LM385-2.5, adjust R3 for I
2. Remove short, adjust R2 for correct reading in
Calibration
1. Short LM385-2.5, adjust R3 for I
2. Remove short, adjust R2 for correct reading in ˚F
centigrade
0˚C–100˚C Thermomemter
0˚F–50˚F Thermomemter
Typical supply current 50 µA
Thermocouple
Type
K
S
OUT
OUT
J
T
=temp at 1µA/˚K
=temp at 1.8 µA/˚K
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00551926
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Seebeck
efficient
(
µ
52.3
42.8
40.8
Co-
V/˚C)
6.4
63.4 150Ω
523 1.24k
432
412 953Ω
(Ω)
R1
8
(Ω)
R2
1k
Adjustment Procedure
1. Adjust TC ADJ pot until voltage across R1 equals Kelvin
2. Adjust zero ADJ pot until voltage across R2 equals the
temperature multiplied by the thermocouple Seebeck
coefficient.
thermocouple Seebeck coefficient multiplied by 273.2.
Across R1
Voltage
@
Micropower Thermocouple Cold Junction
15.60
12.77
12.17
1.908
(mV)
25˚C
Across R2
Voltage
14.32
11.78
11.17
1.766
(mV)
Compensator
00551906