NT Thermistor (high temperature, high sensitivity, glass encapsulated)

Semitec’s glass encapsulated NT-4 series thermistor features high heat resistance and high sensitivity. Compared with conventional thermistors, the NT-4 thermistors are smaller, faster in response, and more reliable which makes them suitable for various applications. SEMITEC’S NT thermistors are fully compliant with RoHS DIRECTIVE2011/65/EU.

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Applications

3D printers, HVAC equipment, water heaters, microwave ovens, home appliances, hybrid vehicles, fuel cell vehicles, automotive electronics, medical, disaster prevention, security, office automation, other high-temperature, high-speed sensing applications

Part number

Dimensions

Rating

Part No.	Rated zero-power resistance^※1※2			B value^※3			Dissipation factor (mW/℃)	Thermal time constant ^※4	Rated power (mW) at 25℃	Operating Temperature range (℃)
Part No.	Temperature (℃)	Resistance (kΩ)	Tolerance	Temperature (℃)	B-value （K）	Tolerance	Dissipation factor (mW/℃)	Thermal time constant ^※4	Rated power (mW) at 25℃	Operating Temperature range (℃)
852NT-4-R050H34G	50	3.485	±3%	0/100	3450	±2%	0.8	6 (0.6)	4	-50～+300
103NT-4-R025H34G	25	10	±3%	25/85	3435	±2%
103NT-4-R025H41G	25	10	±3%	25/85	4126	±2%
493NT-4-R100H40G	100	3.3	±3%	0/100	3970	±2%
503NT-4-R025H42G	25	50	±3%	25/85	4288	±2%
104NT-4-R025H42G	25	100	±3%	25/85	4267	±2%
104NT-4-R025H43G	25	100	±3%	25/85	4390	±2%
204NT-4-R025H43G	25	200	±3%	25/85	4338	±2%
234NT-4-R200H42G	200	1	±3%	100/200	4537	±2%
504NT-4-R025H45G	25	500	±3%	25/85	4526	±2%
105NT-4-R025H46G	25	1000	±3%	25/85	4608	±2%

※1 Rated zero-power resistance at each temperature.
※2 Other resistance tolerance is also available, please ask us.
※3 B value: determined by rated zero-power resistance at each temperature.
※4 Time when thermistor reached 63.2% of the temperature difference. The value is measured in the air. (silicon oil)

How to use

Thermistor is a generic term for Thermally Sensitive Resistor, a semiconductor component whose resistance value changes significantly with changes in temperature.
An NTC thermistor whose resistance value decreases with increasing temperature (having a negative temperature coefficient) is generally called a thermistor.
Thermistors are ceramic semiconductors made mainly from metal oxides and sintered at high temperatures. Various shapes and properties are available depending on the manufacturing method and structure. They are widely used for temperature measurement and temperature compensation.

Figure 1 shows a typical circuit example when using a thermistor.

Fig. 1 Example of a circuit using a thermistor

One example of measuring temperature with a thermistor is to input the voltage between the terminals of the thermistor to an AD converter, convert it to a digital signal, and convert it to temperature using a microcontroller.
Since the resistance value change of a thermistor with respect to temperature is nonlinear, a circuit consisting of a thermistor and a fixed resistor connected in series, as shown in Figure 1, is used to linearize the voltage change of the output voltage Vth.

The thermistor output voltage Vth shown in Figure 1 is calculated as Vth = Vcc × R/(Rth + R), where Vcc is the power supply voltage, Rth is the resistance value of the thermistor, and R is the resistance value of the fixed resistor in series, to give the temperature detected by the thermistor.
The resistance R to be connected in series with the thermistor can be selected by the following formula based on the actual temperature range to be measured.

RL: Temperature range Thermistor resistance value at minimum temperature
RM: Temperature range Thermistor resistance value at intermediate temperature
RH: Temperature range Thermistor resistance value at maximum temperature

As an example, if an AT thermistor (103AT-2) is used for temperature detection in the temperature range 0℃ to 60℃, the resistance value of the fixed resistor connected in series with the thermistor is calculated to be 6.4 kΩ from the following formula.

Ｒ_L　 0℃：27.28kΩ

Ｒ_M　30℃：8.313kΩ

Ｒ_H　60℃：3.020kΩ

Graph 1 shows that when a thermistor is used in combination with a fixed resistor (6.4 kΩ), the output voltage Vth is linearized with respect to temperature change over the temperature range (0℃ to 60℃), thereby improving the precision of temperature detection.

Graph 1 Linearization of output voltage Vth with respect to temperature change

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