SCK20-0120 Datasheet | NTC

w w w D .a S th c k e o r . e t NTC POWER THERMISTOR, SCK SERIES Meritek Thermal dissipation coefficient( δ ) The thermal dissipation coefficient is the ratio, normally expressed in milliwatts per degree C (m W/o C), at a specified ambient temperature, of a change in power dissipation in a thermistor to the resultant body temperature change. (δ =VXI/∆T) Surge energy Surge energy is the maximum energy of pulses. The thermistor is capable of tolerating surge energy more than 1000 times with the resistance changing rates within ± 10%. This energy varies with voltage and capacitance. Thermal time constant( t ) The thermal time constant is the time required for a thermistor to change 63.2 percent of total difference between its initial and final body temperature when subjected to a step function change in ambient temperature under zeropower condition and is normally expressed in seconds. Storage temperature range:- 40 to +125 o C o Operating temperature range:- 30 to +125 C DERATING CURVE OF SURGE CURRENT LIMITING THERMISTOR The maximum power of a thermistor will decrease with the change of ambient temperature.(See Fig.G) Material constant(B) The material constant of a NTC thermistor is a measure of its resistance at one temperature pared to its resistance at a different temperature. Its value may be calculated by the formula shown below and is expressed in degrees kelvin (o K ). The reference temperature used in this formula for determining material constant rating of Meritek’s thermistor is 298.15'o K and 323.15 o K B=Ln(R1/R 2)/( 1/T1-1/T2 ) Temperature coefficient of resistance (α ) The temperature coefficient of resistance is the ratio at a specified temperature, T, of the rate of change of zero-power resistance with temperature to the zeropower resistance of the thermistor. The temperature coefficient is monly expressed in percent per degree C(%/o C). α =I /R d R/d T O.03 w /D w / p : t h a w t s D h p e . d e a f t S h e 4 e U tn / e .t .Data...