High precision thermometer MIJ-NLTP

Overview

The high-precision thermometer MIJ-NLTP by simply applying a power supply voltage and outputting a voltage and MIJ-NLTP realizes high-precision temperature measurements. It can be used at temperatures other than atmospheric temperature, soil temperature, and high temperatures that do not exceed 120 ° C.
Generally, it is a standard practice to use a resistance temperature detector (platinum thermometer) to measure temperature with high accuracy, but since it is a principle to use the temperature characteristics of the resistance value of Pt as it is as a thermometer, it is actually used.
In atmospheric measurements, with a Pt100 probe with a wind speed of 0 m / s and an outer diameter of 3 mm, the error due to self-heating when a current of 1 mA is passed is often +0.1 degrees (De Podesta et al. [1]). This issue is historically ignored and still ignored now on. Since the mid point of the calibration of Pt100 is performed in water, the above error exists in the atmosphere even if it is Pt100 after calibrationdue to the difference in heat capacity between air and water. With Pt1000, the current consumption is equivalent to 10 times that of Pt100, so it cannot be ignored. This issue can only be reduced by reducing power consumption and cannot be improved with a resistance type thermometer.
MIJ-NLTP reduced power consumption to 12μA ( temperature sensitive part.). It means self-heating be +0.0012 degrees.
+0.1(degree) * {12*10^6(A) / 1*10^3(A) = 0.0012(degrees)
In addition, it requires the incorporation of external wiring such as full or half bridges and shunt resistors, making the connection to the data logger a complex task. Or use a dedicated data logger compatible with Pt100, which is generally expensive and not versatile. MIJ-NLTP is a next-generation IC thermometer capable of high-precision temperature measurement, and can be easily connected to a general-purpose data logger without the need for such complicated work.

Reference:
M. de Podesta, S. Bell, R. Underwood, Air temperature sensors: dependence of radiative
errors on sensor diameter in precision metrology and meteorology,Metrologia 55 (2018) 229–244. [1]

Feature

・High sensitivity -0.1939℃/mV

・Fast response t63.2=2.6 seconds at Static Water

・ Accuracy ±0.05℃ that exceeds Pt100 Class  AA standard

・Low power consumption 27.6μW(Overall, Max)

Applications

・Weather

・Soil

・Soil physics

・Outdoor and indoor environment measurement

STRONG POINT

・Measurement accuracy ±0.05℃ (typical at 20~40℃), ±0.12℃ ( -60~100℃)

・Measurement accuracy over the measurement range of -55 to 110 ° C. It better than the Pt100 Class AA standard (JIS C 1604: 2013).

・The temperature measuring part: φ3 x 40 mm SUS Thermowell, which realizes low heat capacity by making it thin and short.

・The IC built into the tip is 12 μA x 2 V = 24 μW (Max). Low self-heating of temperature measuring part

・Output range from 520 to 1375 mV. This is ideal for the measurement range of many general purpose data loggers

・Resin is used for materials other than thermowell. It reduces effects of radiant heat from the outside

MIJ-NLTP Accuracy vs Temperature

Temperature Calculations (Temperature conversion formula)

The voltage output for NLTP temperature is given in True Temp (deg.) In the error table located at top of this page. This is the true value. This temperature characteristic is not a linear relationship, but is expressed as a cubic expression as a result of calculation by the least squares method.

・ Optimal cubic equation (Eq.A) at -20 to 110 ° C
Temp (℃) = -0.000000001809628*(mV)^3-0.000003325395*(mV)^2-0.1814103*(mV)+205.5894

・ Easy-to-use linear equation (Eq.B) at -20 to 110 ° C
Temp (℃) = -0.1939*(mV)+212.81

We have prepared an NLTP Calculation sheet that allows you to easily perform calculations simply by inputting the voltage output.

Optional Battery Pack

NLTP-BTTKIT(External power supply
(Power box with switch+ CR2032battery + 2 & 3 pole one-touch connector

Battery Life:1.8 year (when supplying continuous power)

MIJ-NLTP Size

DATA LOGGER

Multi-channel logger MIJ-01
Simultaneous measurement with other parameters is possible

1-channel logger MIJ-12
Possible to set at multiple points

Compatible with third-party loggers (Logger must have functiion of Input F.S.0~5V)

Response Data

τ
(%)
Air 0m /s
(seconds)
Air 0.2m/s
(seconds)
Air 1.0m/s
(seconds)
Air 2.0m/s
(seconds)
Static Water
(seconds)
0% 0 0 0 0 0
50% 55.6 30.7 14.3 12.1 1.8
60% 76.9 38.8 18.6 15 2.4
63.2% 85.1 42.1 20.1 16.2 2.6
90% 233.3 90.8 44.9 34.3 6.4
99% 658.9 195.5 97.5 66.9 23.0
99.9% 856.4 307 174.2 103.8 30.1

MIJ-NLTP Specification

Measurement principle CMOS-Integrated Circuit
Measurement accuracy ±0.05℃ (typical at 20~40℃)
±0.12℃ ( -60~100℃)
Self-heating error at static air +0.0012 degrees
Measurement range -55 to 110℃
Response speed 𝜏(63.2% at static water) = 2.6 seconds
𝜏(63.2% at static air) = 85.1 seconds
Raise speed 600μ seconds (0.0006 seconds, time from power-on to stable output
Shape Overall length 80mm (including temperature sensitive part 40mm, not including cable)
Body diameter φ8 mm, temperature sensitive part diameter φ3 mm
Materials Body: POM, Temperature sensitive part: SUS304
Cable length Standard 5meter (Extension can be specified as an option)
Cable diameter Outer diameter φ4.6mm, conductor AWG22(0.64mm, 0.32mm2)
Terminal finish Bar terminal (Nichifu TE0.5-8 white)
Output voltage range 1375.219mV at -55 ℃, 520.551mV at 110 ℃
Power supply voltage range Can be used with 2.5 to 30VDC and continuous voltage application
Power supply current
13.8μA max (Power supply circuit 1.8μA + temperature sensitive part 12μA)
Power consumption Total power consumption 34.5μW
temperature sensitive part power consumption 24μW
Voltage temperature conversion formula

3rd order transfer (-55 to 110 ℃):
Temp (℃) = -0.000000001809628*(mV)^3-0.000003325395*(mV)^2-0.1814103*(mV)+205.5894

1st order transfer (-55 to 110 ℃):
Temp (℃) = -0.1939*(mV)+212.81

Weight 166g(Including 5m cable)
Pin wiring Red/Preheat(Power)、White/signal、Black/GND(COM)
Preheat time ≧600μ seconds (0.0006 seconds)
Optional

NLTP-BTTKIT(External power supply)
(Power box with switch+ CR2032battery + 2 & 3 pole one-touch connector

Battery Life:1.8 year (when supplying continuous power)