LM385M3-1.2 National Semiconductor, LM385M3-1.2 Datasheet - Page 6

• Manufacturer Part Number: LM385M3-1.2
• Description: IC, SHUNT V-REF, 1.235V, 2%, 3-SOT-23
• Manufacturer: National Semiconductor

Specifications of LM385M3-1.2

• Topology: Shunt
• Reference Voltage: 1.23V
• Reference Voltage Tolerance: 25mV
• Voltage Reference Case Style: SOT-23
• No. Of Pins: 3
• Temperature Coefficient: 150ppm/°C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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METER THERMOMETERS
Calibration
1. Short LM385-1.2, adjust R3 for I
2. Remove short, adjust R2 for correct reading in centigrade
Calibration
1. Short LM385-1.2, adjust R3 for I
2. Remove short, adjust R2 for correct reading in °F
Micropower Thermocouple Cold Junction Compensator
0°C−100°C Thermometer
0°F−50°F Thermometer
OUT
OUT
= temp at 1μA/°K
= temp at 1.8μA/°K
551830
551828
551831
6
†I
I
*2N3638 or 2N2907 select for inverse H
†Select for operation at 1.3V
‡I
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.
Typical supply current 50μA
Q
Thermocoup
Q
Q
at 1.6V 2.4mA
at 1.3V 500μA
≃ 600μA to 900μA
Type
le
K
S
J
T
Lower Power Thermometer
Coefficient (Ω) (Ω)
Seebeck
(μV/°C)
52.3
42.8
40.8
6.4
63.
R1 R2
52
43
41
3
2
2
4
FE
1.2
3Ω
0Ω
4k
1k
95
15
5
Voltage
@ 25°C
Across
15.60
12.77
12.17
1.908
(mV)
R1
551829
Voltage
Across
14.32
11.78
11.17
1.766
(mV)
R2