104AT-2 Semitec, 104AT-2 Datasheet - Page 22

• Manufacturer Part Number: 104AT-2
• Description: AT thermistor, 100KOhm
• Manufacturer: Semitec

22
Thermal time constant
If ambient temperature of a thermistor is changed
to T
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 ;
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 1 C raise by heat in a thermistor.
P is applied electric power.
Resistance-temperature characteristics
The theoretical characteristics of a thermistor is expressed by following equation.
R
t is rised temperature of the thermistor.
1
T
B
1
2
P
R
from T
t
( % / C)
2
(mW/ C)
exp B
MARK
0.01
2
100
1.0
0.1
10
suddenly, temperature of the thermistor
200
T
1
160
1
B : 3150K
T
1
100
2
50
Temperature ( C)
25
0
25
R
R
Maximum permissible current
If the maximum permissible current flows to a
thermistor at 25 C, temperature of the thermistor
rises to 200 C, (160 C). When ambient temperature is
above 25 C, the maximum permissible current shall be
over reduced as the maximum permissible current
reduction curve.
1
2
is the zero-power resistance at absolute temperature T
is the zero-power resistance at absolute temperature T
New Power Thermistor MARK
Power Thermistor
MARK
0.01
100
1.0
0.1
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
10
200
20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200
160
10 0
B : 2900K
10
100
20
30 40 50 60 70 80 90 100 110 120 130 140 150 160
50
D TYPE
Temperature ( C)
25
Ambient temperature ( C)
Ambient temperature ( C)
0
25
W TYPE
1
2
Power Thermistor
20.0
10.0
0.05
0.03
0.02
5.0
3.0
2.0
1.0
0.5
0.3
0.2
0.1
Reliability tests
MARK
Dry heat test
Test sample is exposed in air at 200 C for 1,000
hours. R25/R25
Damp heat test
Test sample is exposed in atmosphere of 95%RH at
40 C for 1,000 hours. R25/R25
Load test
Test sample is applied the maximum rating current
in air at 25 C for 1,000 hours. R25/R25
Change of temperature
Test sample is given 10 times of the following
temperature cycle,
minutes
minutes.
POWER THERMISTOR
Dry heat test
Test sample is exposed in air at 160 C for 1,000
hours. R25/R25
Damp heat test
Test sample is exposed in atmosphere of 95%RH at
40 C for 1,000 hours. R25/R25
Load test
Test sample is applied the maximum rating current
in air at 25 C for 1,000 hours. R25/R25
Change of temperature
Test sample is given 10 times of the following
temperature cycle,
minutes
minutes.
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 25 C and 85 C.
160
R25/R25
R25/R25
200 C for 30 minutes
160 C for 30 minutes
40 C for 30 minutes
30 C for 30 minutes
100
B : 3250K
10%
10%
50
20%
10%
25
Temperature ( C)
room temperature for 5
room temperature for 5
room temperature for 5
room temperature for 5
0
10%
10%
30
20%
10%