NTC

NTC THERMISTOR

24

1200 1500

NTC

Rt

25

B

B

R25

B=ln RT1 / ( 1 1 )= T1 T2 ln RT1

Rt2 T1 T2 T2 T1 RT2

RT1 T1

RT2 T2

15K )

B 25 ( 298.

50 ( 323.15K )

,B

T

T=

1

RT

DRT =

DT

B

T2

TT

RT-

T

BB

T

(K

)

NTC

NTC THERMISTOR

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:

B=ln RT1 / ( 1 1 =) T1 T2 ln RT1

Rt2 T1 T2

T2 T1 RT2

In this formula: RT1 is the resistance at Zero-power when the

temperature is T1

RT2 is the resisrtance at Zero-power when the temperature is

T2 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.

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:

T=

1

RT

DRT =

DT

B

T2

In this formula, " " stands for the resistance-temperature

coefficient at Zero-power when the temperature is T:

RT stands for the resistance value at Zero-power when the

temperature is T

T stands for thetemperature(in K)

B stands for B value

1

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Imax Max steady state current.

The maximun allowable continuous current passing through

thermistor at 25 .

=P/T

,

63.2%

C

=C /

USB

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.

Thermal Time Constant

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 " =C/ " .

APPLICATIONS

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.

2

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NTC

NTC THERMISTOR

(NTC)

Surge-Arrestor NTC Thermistor

F E AT U R E S

Small in size,high-powered, and very capable of bringing

down the surge current;

Quick in reaction;

B High in B value and low in residual current;

Long service life and high reliability;

High coefficient of safety and wide range of application.

HOW TO ORDER

NTC

Negative Temperature Cofficient Resistor

10

10

Resistance Value:10

D 13

13

Diameter of Chip: 13

DIMENSIONS (mm)

A

D

F

C

E

Type

D-20

D-15

D-13

D-11

D-9

D-7

A

MAX

22

16.5

14.5

12.5

10.5

8.5

C1

7.5/10

7.5

7.5

7.5

7.5

5.0

1

2GH

13

2A

D

MAX

7

6

6

5

5

5

E 0.05

1.0

1.0

0.8

0.8

0.8

0.5

E 0.6

(mm)

F

MAX

4

4

4

4

4

4

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.

3

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