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# E-501 View Datasheet(PDF) - SEMITEC Corporation

 Part Name Description Manufacturer E-501 SURGE ABSORBERS , SENSORS AND MODULES , THERMISTORS SEMITEC Corporation E-501 Datasheet PDF : 44 Pages
 First Prev 21 22 23 24 25 26 27 28 29 30 Next Last Thermal time constant If ambient temperature of a thermistor is changed to T1 from T2 suddenly, temperature of the thermistor changes slowly. The time constant means the time when temperature of the thermistor reaches 63% of the temperature difference. Residual resistance If current is flowed through a thermistor, any heat will be generated in the thermistor by which its resistance will be decreased, however, a decrease of a resistance will be stabilized at a saturation resistance value which is determined by impressed electric power and a dissipation constant. The residual resistance value means maximum saturation resistance value when the maximum permissible current is flowed through the thermistor. Temperature coefficient The temperature coefficient of a thermistor is expressed by the following equation ; Ϫ B T2 ( % / Њ C) Dissipation factor If small voltage is applied to a thermistor, small current will flow which produce enough heat in the thermistor. Dissipation factor is electric power which make 1Њ C raise by heat in a thermistor. ␦ϭ P ⌬t (mW/ Њ C) P is applied electric power. ⌬t is rised temperature of the thermistor. Maximum permissible current If the maximum permissible current flows to a thermistor at 25ЊC, temperature of the thermistor rises to 200ЊC, (160ЊC). When ambient temperature is above 25ЊC, the maximum permissible current shall be over reduced as the maximum permissible current reduction curve. New Power Thermistor MARK 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 Ambient temperature (ЊC) Power Thermistor 1.2 1.1 1.0 0.9 0.8 W TYPE 0.7 0.6 D TYPE 0.5 0.4 0.3 0.2 Ϫ10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 Ambient temperature (ЊC) Reliability tests MARK Dry heat test Test sample is exposed in air at 200ЊC for 1,000 hours. ⌬R25/R25 Ϯ20% Damp heat test Test sample is exposed in atmosphere of 95%RH at 40ЊC for 1,000 hours. ⌬R25/R25 Ϯ10% Load test Test sample is applied the maximum rating current in air at 25ЊC for 1,000 hours. ⌬R25/R25 Ϯ20% Change of temperature Test sample is given 10 times of the following temperature cycle, Ϫ40ЊC for 30 minutes room temperature for 5 minutes 200ЊC for 30 minutes room temperature for 5 minutes. ⌬R25/R25 Ϯ10% POWER THERMISTOR Dry heat test Test sample is exposed in air at 160ЊC for 1,000 hours. ⌬R25/R25 Ϯ10% Damp heat test Test sample is exposed in atmosphere of 95%RH at 40ЊC for 1,000 hours. ⌬R25/R25 Ϯ10% Load test Test sample is applied the maximum rating current in air at 25ЊC for 1,000 hours. ⌬R25/R25 Ϯ10% Change of temperature Test sample is given 10 times of the following temperature cycle, Ϫ30ЊC for 30 minutes room temperature for 5 minutes 160ЊC for 30 minutes room temperature for 5 minutes. ⌬R25/R25 Ϯ10% Resistance-temperature characteristics The theoretical characteristics of a thermistor is expressed by following equation. R1 ϭ R2 exp B 1 T1 Ϫ 1 T2 R1 is the zero-power resistance at absolute temperature T1 R2 is the zero-power resistance at absolute temperature T2 B is constant which depends on the material used to make the thermistor. Unless otherwise specified, all values of B are determined from measurements made at 25ЊC and 85ЊC. MARK 100 B : 3150K 10 1.0 0.1 0.01 200 160 100 50 25 0 Ϫ25 Temperature (ЊC) MARK 100 B : 2900K 10 1.0 0.1 0.01 200 160 100 50 25 0 Ϫ25 Temperature (ЊC) Power Thermistor B : 3250K 20.0 10.0 5.0 3.0 2.0 1.0 0.5 0.3 0.2 0.1 0.05 0.03 0.02 160 100 50 25 0 Ϫ30 Temperature (ЊC) 22