ntc ntc thermistor 24 1200 1500 b=ln r t1 r t1 r t2 r t2 / () 1 t 1 t 1 t 1 1 t 2 t 2 t 2 = ln ntc rt r 25 25 b b t rt1 rt2 b 25 ( 298. 15k ) 50 ( 323.15k ) ,b t1 t2 t r- t t(k) bb t t b=ln r t1 r t1 r t2 r t2 / () 1 t 1 t 1 t 1 1 t 2 t 2 t 2 = ln t = 1 r t dr dt t b t 2 = t = 1 r t dr dt t b t 2 = outline this is a negative temperature coefficient resistor whose resistance changes with ambient temperature changes. thermistor comprises 2or 4 kinds of metal oxides of iron, nickel,cobalt, manganese and copper, being shaped and sintered at high temperature(1200 to 1500 ) critical technical parameters of ntc thermistor rt---resistance value at zero-power it's a resistance which is got at a fixed temperature on a basis of a testing power which causes resistance to vary in a range which can be ignored in relation to the total testing eror. r25---resistance value at rated zero-power the design resistance of the thermistor usually refers to the resistance value got at zero-power at 25 , which is usually indicated on the thermistor. b value b value stands for the thermal exponent at a negative temperature coefficient. lt's defined as a ratio of the balance between the natural logarithms of resistance values at zero- power to the balance between the reciprocals of the two temperatures.the formula is as below: resistance-to-temperature coefficient at zero-power it refers to the ratio of changes of a thermistor. resistance value at zero-powerwhen the temperature, to the resistance value at zero-power the formula is as below: in this formula, " " stands for the resistance-temperature coefficient at zero-power when the temperature is t: r stands for the resistance value at zero-power when the temperature is t t stands for thetemperature(in k) b stands for b value t in this formula: r is the resistance at zero-power when the temperature is t r is the resisrtance at zero-power when the temperature is t unless otherwise specified, b value is got by calculating the zero-power resistances at 25 ( 298.15k ) and50 ( 323.15k ) . it's not a firm constant within the range of working temperature. t1 1 t2 2 1 ntc ntc thermistor free datasheet http://
2 , =p/t 63.2% c =c / dissipation coefficient it's the ratio of the changes with a thermistor dissipation power, in a pre-set ambient temperature, to the changes with the temperature. the formula is as below: = p/ t changes in response when the ambient temperature changes, within the ranges of the working temperature. applications thermal time constant =c/ at zero-power and when amutatio occurs with the temperature, the time "t", which is-spent for finishing 63.2% of the gap between the beginning temperature and the ending temperature in the thermistor. is directly proportional to"c",the heat capacity of the thermistor, and is inversely proportional to , the dissip ation constant. that is " " . usb imax max steady state current. the maximun allowable continuous current passing through thermistor at 25 . conversion power supply, switch power, ups power, kinds of electric heter, electronic energy-saving lamps, electronic ballast etc all kinds of power cicuit proterction of electronic equipments, filament proterction of crt, bulb and other lighting lamps. free datasheet http://
3 (ntc) b dimensions (mm) 1132ae0.6 2gh remarks:1 "e"value may be 0.6 for resistors for which the chip's diameter is 13 and the working current is 2a. 2 "g"column and "h" column stand for bend dimensions of the lead. howtoorder surge-arrestor ntc thermistor features small in size,high-powered, and very capable of bringing down the surge current; quickinreaction; high in b value and low in residual current; long service life and high reliability; high coefficient of safety and wide range of application. negative temperature cofficient resistor 10 resistance value:10 13 diameter of chip: 13 ntc 10 d13 type (mm) a max c1 d max e0.05 f max d-20 d-15 d-13 d-11 d-9 22 16.5 14.5 12.5 10.5 7.5/10 7.5 7.5 7.5 7.5 7 6 6 5 5 1.0 1.0 0.8 0.8 0.8 4 4 4 4 4 a d f c e ntc ntc thermistor d-7 8.5 5.0 5 0.5 4 free datasheet http://
4 specifications & properties model r25 20%( ) (a) max steady- current(a) power dissipation coe- fficient(mw/ ) time constant (s) ntc 5d-7 ntc 8d-7 ntc 10d-7 ntc 16d-7 ntc 22d-7 ntc 2.5d-9 ntc 3d-9 ntc 5d-9 ntc 8d-9 ntc 10d-9 ntc 16d-9 ntc 22d-9 ntc 25d-9 ntc 35d-9 ntc 50d-9 ntc 60d-9 ntc 80d-9 ntc 100d-9 ntc 120d-9 ntc 200d-9 ntc 300d-9 ntc 2.5d-11 ntc 3d-11 ntc 5d-11 ntc 8d-11 ntc 10d-11 ntc 16d-11 ntc 2.5d-13 ntc 3d-13 ntc 5d-13 ntc 10d-13 ntc 16d-13 ntc 3d-15 ntc 4d-15 ntc 5d-15 ntc 8d-15 ntc 10d-15 5 8 10 16 22 2.5 3 5 8 10 16 22 25 35 50 60 80 100 120 200 300 2.5 3 5 8 10 16 2.5 3 5 10 16 3 4 5 8 10 0.241 0.436 0.572 0.897 1.083 0.128 0.133 0.236 0.382 0.476 0.688 0.899 0.914 1.103 1.265 1.521 2.108 2.576 3.115 5.900 9.150 0.120 0.126 0.288 0.301 0.395 0.488 0.099 0.112 0.136 0.271 0.368 0.094 0.128 0.132 0.196 0.255 10 9 9 9 8 11 11 11 11 11 11 11 12 12 11 11 11 11 11 10 10 13 13 13 13 14 14 13 14 15 15 16 18 20 20 20 20 30 28 27 27 27 35 35 35 34 34 32 30 30 30 30 30 30 30 30 32 32 46 45 45 45 47 50 60 60 68 65 60 76 76 76 80 85 2 1.5 1 0.7 0.6 4 4 3 2 2 1 1 1 1 1 1 0.8 0.8 0.8 0.5 0.5 5 5 4 3 3 2 6 6 5 4 3 7 6 6 5 5 () approx r of max.cur.( ) ntc 8d-13 8 0.256 15 65 4 ntc 16d-15 16 0.307 19 77 4 ntc 3d-15 3 0.079 24 100 8 ntc 5d-20 5 0.106 23 87 7 ntc 8d-20 8 0.157 23 105 6 ntc 10d-20 10 0.194 23 118 6 free datasheet http://
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