Design and specifications are each subject to change without notice. Ask factory for the current technical specifications before purchase and/or use.
Should a safety concern arise regarding this product, please be sure to contact us immediately.
NTC Thermistors
T (˚C)
0
–20
–40
20 40 60 80 100 120 140
1000
RT/R25
100
10
1
0.1
0.01
0.001
5000
6000
4000
3000
2000
B=1000
R (Ω)
T (˚C)
2.4
1
2.9 3.4 3.9 4.4
125 85 50 25 0 –20 –40
10000000
1000000
100000
10000
10
1000
100
E
R
T
J
0
E
R
1
0
3
□
B
2
5
/
5
0
=
4
2
5
0
E
R
T
J
0
E
R
1
0
3
□
B
2
5
/
5
0
=
4
2
5
0
E
R
T
J
0
E
G
1
0
3
□
A
B
2
5
/
8
5
=
3
4
3
5
E
R
T
J
0
E
G
1
0
3
□
A
B
2
5
/
8
5
=
3
4
3
5
E
R
T
J
0
E
P
4
7
3
□
B
2
5
/
5
0
=
4
0
5
0
E
R
T
J
0
E
V
1
0
4
□
B
2
5
/
5
0
=
4
7
0
0
E
R
T
J
0
E
V
1
0
4
□
B
2
5
/5
0
=
4
7
0
0
E
R
T
J
0
E
A
1
0
1
□
B
2
5
/
5
0
=
2
8
0
0
E
R
T
J
0
E
A
1
0
1
□
B
2
5
/
5
0
=
2
8
0
0
E
R
T
J
0
E
T
1
0
2
□
B
2
5
/
5
0
=
4
5
0
0
E
R
T
J
0
E
T
1
0
2
□
B
2
5
/
50
=
4
5
0
0
T
1
(
×10
–3
K
–1
)
E
R
T
J
0
E
P
4
7
3
□
B
2
5
/
5
0
=
4
0
5
0
The NTC Thermistors
NTC Thermistors is a negative temperature coefficient resistor that significantly reduces its resistance value as the heat/
ambient temperature rises. Thermistors is sintered in high-temperature (1200 °C to 1500 °C), and manufactured in
various shapes. It’s comprised of 2 to 4 kinds of metal oxides: iron, nickel, cobalt, manganese and copper.
●
For temperature measurement or temperature
detection : Thermometer, temperature controller
●
For temperature compensation : Transistor, transistor
circuit, quarts oscillation circuit, and measuring
instruments
●
Temperature Coeffi cient of Resistance is negative,
and it’s extremely large (–2.8 to –5.1 [%/°C]).
●
Various shapes, especially compact size
components are available.
●
Selection of resistance vale is comparatively free, it’s
available from several tens Ω to several hundred kΩ.
Fig. 1
Fig. 2
Thermistor is a resistor sensitive to temperature that is
utilizing the characteristic of metal oxide semiconductor
having large temperature coeffi cient.
And its temperature dependency of resistance value is
indicated by the following equation :
R=R
0
exp B
.....................................
(1)
T
0
: Standard Temperature 298.15 K(25 °C)
R
0
: Resistance at T
0
[K]
B : Thermistor Constant [K]
Temperature coef fi cient (a) in general meaning is indicated
as follows :
a
=
....................................................................
(2)
Since the change by temperature is considerably large, a is
not appropriate as a constant. Therefore, B value (constant)
is generally used as a coeffi cient of thermistors.
1
T
1
T
0
( )[ ]
B
T
2
The relation between resistance and temperature of a
thermistor is linear as shown in Fig. 2. The resistance
value is shown in vertical direction in a logarithmic scale
and reciprocal of absolute temperature (adding 273.15 to
centigrade) is shown in horizontal direction.
The B value (constant) determines the gradient of these
straight lines. The B value (constant) is calculated by using
following equation.
B =
.......................................................
(3)
R
1
: Resistance at T
1
K
R
2
: Resistance at T
2
K
When you calculate this equation, you’ll fi nd that B value
is not exactly constant. The resistance is expressed by
the following equation :
R = AT
–C
exp D/T
.............................................................
(4)
In (4), C is a small positive or negative constant and quite
negligible except for use in precision temperature-measuring
device, therefore, the B value can be considered as constant
number.
In Fig. 1, the relation between the resistance ratio
R
T
/R
25
(R
25
: Resistance at 25 °C, RT : Resistance at T °C)
and B Value is shown with T °C, in the horizontal direction.
1
T
1
1
T
2
k
nR
1
–
k
nR
2
Features
Physical Characteristics of NTC Thermistors
Major Characteristics of NTC Thermistors
Recommended Applications
May. 201502
