Electronic Components Datasheet Search
 Selected language English  ▼

## 4W-25 Datasheet(PDF) 6 Page - List of Unclassifed Manufacturers

 Part No. 4W-25 Description THERMOPILE TYPE INFRARED SENSOR Download 44 Pages Scroll/Zoom 100% Maker ETC1 [List of Unclassifed Manufacturers] Homepage Logo

 6 page 6 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 B:3350 B:3400 1k 10k 100k Temperature(1/ Tx10 3) THERMISTOR "Thermistor" is the generic name given to thermally sensitive resistors. Negative temperature coefficient thermistor is generally called as thermistor. Thermistor is a semiconducting ceramic resistor produced by sintering the materials at high temperature and made mainly from metal oxide. Depending on the manufacturing method and the structure, there are many shapes and characteristics for various purposes such as temperature measurement, temperature compensation and etc. The thermistor resistance values, unless otherwise specified, are classified at a standard temperature of 25 C. B constant is calculated from the resistance values at 25 C and 85 C. The resistance of a temperature is solely a function of its absolute temperature. Since electrical power being dissipated within a temperature might heat above its ambient temperature and thereby reduce its resistance, it is necessary to test for resistance with temperature. The resistance so measured is called RT, which means the resistance at essentially zero-power. The mathematical expression which relates the resistance and the absolute temperature of a thermistor is as follows: Ra Rb exp B 1 T1 1 T2 B T2 Ra T1 Where: is the resistance at absolute temperature is the resistance at absolute temperature Rb T2 B is a constant which depends on the material of the thermistor Unless otherwise specified,all values of B are determined from measurements made at 25 C and 85 C. The temperature coefficient of resistance is expressed in the following equation: 100 (%/ C) Resistance -Temperature Characteristics Dissipation factor Thermal time constant Dissipation factor ( ) is power in milliwatts required to raise thermistor temperature 1 C. Measured with thermistor suspended by its leads in a specified environment. t:Raise temperature( C) t P (mW/ C) P :Power(mW) Thermal time constant ( a) is the time required by a thermistor to change 63% of the difference between its initial and final temperature. Measured with thermistor suspended by its leads in specified environment. 95 87 63 a 2 a 3 a 5 a Time (s)