POWER
THERMISTOR
The POWER THERMISTOR is a device for
suppressing inrush current to an electric
circuit. Circuits including electric bulbs or
capacitors induce a inrush current more
than 100 times the normal current when the
circuit switch is turned on. The POWER
THERMISTOR in the circuits protects
electric equipments from being damaged
by limiting the inrush current.
MARK is a NEW POWER THERMISTOR
featuring smaller size and larger energy
capacity to meet severe requirements in
inrush current suppression.
There is the tendency of miniturization in
low power switching power supply, and
MARK is effectively applicable for the
needs, though the camparatively larger
sized fixed resistors (ceramic coat) are
used now.
Application
The power thermistor will suppress inrush current
which is caused by a capacitor, filament for a bulb,
inverter for fluorescent lamp, a heater and etc., also
will control fan motor speed of cooler for electric
circuit.
Especially MARK was developed to use for power
supply of TV, VCR instead of cement resistor.
How to use the power thermistor
Accordingly, suitable thermistors are 6D-22, 5D-18
and 8D-18, and if we consider in the points of small
time constant which means a small size and large
effect for suppressive current which means large
rated zero-power resistance, 8D-18 is the most
suitable one.
Use the following circuit in the power supply for 100V
and 200V.
SW
1
SW
t
I
O
t
C
1
V
E
L
C
2
SW
2
V
E
C
L
SW
2
: ON (200V), OFF (100V)
Input voltage
:
AC 100V 10%
Steady state current
:
2A
Capacitor
:
2000 F
Ambient temperature
:
Max.55 C
Suppressive current
:
Max.30A at 25 C
t
The most suitable power thermistor for the above
circuit is required to fulfill the following terms and
conditions.
1. The permissible current at ambient temperature of
55 C should be over 2A.
2. The thermistor resistance for suppressive current
which becomes below 30A should be over 4.2
ohm from the under-mentioned formula.
2 V
E
1.1
30
R
C
R
25
R
C
:
Intial resistance value in the circuit is 1 ohm
(100V/100A)
R
25
:
Rated zero-power resistance at 25 C
3. Max. capacitance shall be over 2000 F at AC 100V.
20
Thermal time constant
Maximum permissible current
Reliability tests
MARK
Dry heat test
If ambient temperature of a thermistor is changed
to T
1
from T
2
suddenly, temperature of the thermistor
changes slowly.
The time constant means the time when temperature
of the thermistor reaches 63% of the temperature
difference.
Residual resistance
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.
New Power Thermistor MARK
1.2
1.1
Current derating ratio
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200
Ambient temperature ( C)
Test sample is exposed in air at 200 C for 1,000
20%
hours. R25/R25
Damp heat test
Test sample is exposed in atmosphere of 95%RH at
40 C for 1,000 hours. R25/R25
10%
Load test
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
satulation resistance value when the maximum
permissible current is flowed through the thermistor.
Temperature coefficient
Test sample is applied the maximum rating current
20%
in air at 25 C for 1,000 hours. R25/R25
Change of temperature
The temperature coefficient of a thermistor is
expressed by the following equation ;
B
( % / C)
T
2
Dissipation factor
Current derating ratio
Test sample is given 10 times of the following
temperature cycle,
40 C for 30 minutes
room temperature for 5
minutes
200 C for 30 minutes
room temperature for 5
minutes.
10%
R25/R25
POWER THERMISTOR
Dry heat test
Power Thermistor
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160
Ambient temperature ( C)
Test sample is exposed in air at 160 C for 1,000
10%
hours. R25/R25
Damp heat test
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 (mW/ C)
t
P is applied electric power.
t is rised temperature of the thermistor.
Test sample is exposed in atmosphere of 95%RH at
40 C for 1,000 hours. R25/R25
10%
W TYPE
Load test
D TYPE
Test sample is applied the maximum rating current
10%
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,
30 C for 30 minutes
room temperature for 5
minutes
160 C for 30 minutes
room temperature for 5
minutes.
10%
R25/R25
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.
Resistance-temperature characteristics
The theoretical characteristics of a thermistor is expressed by following equation.
R
1
R
2
exp B
1
T
1
1
T
2
R
1
is the zero-power resistance at absolute temperature T
1
R
2
is the zero-power resistance at absolute temperature T
2
MARK
100
Resistance change ratio
B : 3150K
MARK
100
Resistance change ratio
B : 2900K
Power Thermistor
20.0
Resistance change ratio
B : 3250K
10.0
5.0
3.0
2.0
10
10
1.0
1.0
1.0
0.5
0.3
0.2
0.1
0.1
0.1
0.05
0.03
0.01
200 160
0.01
200 160
0.02
100
50
25
0
Temperature ( C)
25
160
100
50
25
0
Temperature ( C)
30
100
50
25
0
Temperature ( C)
25
21
Specifications (Disk type)
R
25
*
( )
3
4
6
4
5
8
10
5
8
16
5
8
10
10
16
22
1
Part No.
B value
*
B
25/85
(K)
3250
3250
3250
3250
3250
3250
3250
3250
3250
3250
3250
3250
3250
3250
3250
3250
2
Maximum
enegy
J
(W-s)
40.0
50.0
80.0
9.0
11.0
18.0
22.0
4.0
6.0
12.0
4.0
6.0
7.0
2.0
4.0
1.0
3D-22
4D-22
6D-22
4D-18
5D-18
8D-18
10D-18
5D-13
8D-13
16D-13
5D-11
8D-11
10D-11
10D-9
16D-9
22D-7
15%
15%
15%
15%
15%
15%
15%
15%
15%
15%
15%
15%
15%
15%
15%
15%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
Maximum
rating
current
at 25 C
(A)
5.4
4.7
3.9
4.1
3.8
3.1
2.8
3.4
2.7
1.9
3.3
2.6
2.4
2.2
1.7
1.4
Residual
*
resistance
( )
0.137
0.182
0.274
0.182
0.228
0.365
0.456
0.228
0.365
0.730
0.228
0.365
0.456
0.456
0.730
1.003
3
Dissipation
factor
(mW/ C)
29.8
30.7
32.4
22.8
24.6
27.2
28.2
20.1
20.3
21.4
19.0
19.8
20.1
17.2
17.4
15.7
Thermal
time
constant
(s)
130
160
220
100
120
150
150
55
65
105
50
70
75
40
50
30
*
4
Rating
temp
( C)
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
160
160
160
160
160
160
160
160
160
160
160
160
160
160
160
160
Maximum capacitance
( F)
AC100V
8,500
11,000
17,000
2,000
2,500
4,100
5,000
900
1,400
2,800
900
1,400
1,800
510
820
310
AC120V
5,900
7,600
11,800
1,350
1,700
2,800
3,400
620
970
1,900
620
970
1,250
350
560
210
AC220V
1,700
2,200
3,500
410
510
840
1,030
180
280
570
180
280
370
100
160
60
AC240V
1,470
1,900
2,950
340
430
710
860
150
240
480
150
240
310
80
140
50
Specifications (Washer type)
R
25
*
( )
1
Part No.
B value
*
2
B
25/85
(K)
3250 5%
3250 5%
Maximum
enegy
J
(W-s)
80
50
Maximum
rating
current
at 25 C
(A)
6.1
7.8
Residual
*
resistance
( )
0.153
0.102
3
Dissipation
factor
(mW/ C)
34.0
36.2
Thermal
time
constant
(s)
220
160
*
4
Rating
temp
( C)
30 200
30 200
Maximum capacitance
( F)
AC100V
17,000
11,000
AC120V
11,800
7,600
AC220V
3,500
2,200
AC240V
2,950
1,900
6W-22
4W-25
6.0 15%
4.0 15%
*
1
*
2
*
3
*
4
R
25
: Rated zero-power resistance value at 25 C.
B value : determined by rated zero-power resistance at 25 C and 85 C.
Residual resistance is the maximum value when maximum rating current is applied.
Time when thermistor temperature reaches 63.2% of the temperature difference. The value is measured in the air.
Part number
Disk type
Dimensions
Disk type
D
Forming lead
Taping
Element diameter : 11
Shape D : Disk type
Resistance at 25 C : 5
T
D
T
Washer type
28 max.
29 max.
(11)
5D-11
DU
5D-11
DU
35 max.
18
0.8
Tin-plated
copper
wire
F
L
H
h
5 D - 11 T3C (F2)
Washer type
25 min.
4 W - 25
Element diameter : 25
Shape W : Washer type
Resistance at 25 C : 4
d
(12)
23 max.
d
3 5
1. Straight lead type
2. Forming lead type
UL approved
(Disk type)
File No. E92669
Thermistor type device
Canadian Standards
(Disk type)
File No. CA97673-1
Class 7950 30 NTC Thermistor
R
D-7
D-9
D-11
D-13
D-18
D-22
Taping
D
9.5max.
11max.
14max.
16max.
21max.
25max.
T
5max.
6max.
8max.
9max.
8max.
W
0
H
13max.
15max.
18max.
20max.
26max.
30max.
W
1
W
2
h
15max.
17max.
20max.
22max.
28max.
32max.
H
1
L
F
L
d
6 1
7.5 1
3 0.2
3.5 0.5
10 1
Taping
P
W
P
P
0
P
1
D-7
15 1
D-9
15 0.3 3.75 0.7 18
1.0
0.5
D-11
D-13 30 1
h
F
1
D
0
t
t
1
h
5min. 9 0.5 3max. 16 0.5 1max. 7.5 0.5 4 0.3 0.6 0.3 1.6max. 0 2
W
W
0
W
2
W
1
P
1
F
1
L
H
1
P
O
D
0
t
1
t
22
Specifications (Disk type)
R
25
*
( )
5.1
8.2
10.0
12.0
16.0
22.0
2.2
3.0
3.9
5.1
8.2
10.0
1.0
2.0
3.0
3.9
5.1
1
Part No.
B value
*
B
25/85
(K)
2900
2900
2900
3150
3150
3150
2900
2900
2900
3150
3150
3150
2900
2900
3150
3150
3150
2
Maximum
enegy
J
(W
.
s)
2.0
2.8
3.4
3.6
4.0
4.8
8.2
8.6
8.0
7.2
7.8
8.2
18.0
21.0
15.0
17.0
18.0
M5R107
M8R207
M10007
M12007
M16007
M22007
M2R210
M3R010
M3R910
M5R110
M8R210
M10010
M1R014
M2R014
M3R014
M3R914
M5R114
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
Maximum
rating
current
at 25 C
(A)
4.6
3.6
3.3
3.6
3.1
2.6
7.4
6.4
5.6
5.7
4.5
4.1
11.9
8.6
8.3
7.4
6.5
Residual
*
resistance
( )
0.18
0.30
0.36
0.24
0.43
0.59
0.08
0.11
0.11
0.14
0.22
0.27
0.04
0.07
0.08
0.08
0.14
3
Dissipation
factor
(mW/ C)
17.0
17.2
17.2
17.5
17.8
18.0
18.9
19.2
19.5
19.2
19.9
20.1
22.0
23.4
23.6
24.5
24.7
Thermal
*
4
time
constant
(s)
20
25
30
25
30
40
40
45
45
40
50
60
65
90
80
95
110
Rating
temp
( C)
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
200
200
200
200
200
200
200
200
200
200
200
200
200
200
200
200
200
Maximum capacitance
( F)
AC100V
400
560
680
560
800
960
1,460
1,720
1,880
1,440
1,560
1,640
3,720
4,200
3,080
3,400
3,600
AC120V
270
380
470
380
550
660
1,130
1,190
1,300
1,000
1,080
1,130
2,580
2,900
2,130
2,360
2,500
AC220V
80
110
140
110
160
190
330
350
380
290
320
330
760
860
630
700
740
AC240V
60
90
110
90
130
160
280
290
320
250
270
280
640
720
530
590
620
*
1
*
2
3
*
4
*
R
25
: Rated zero-power resistance value at 25 C.
B value : determined by rated zero-power resistance at 25 C and 85 C.
Residual resistance is the maximum value when maximum rating current is applied.
Time when thermistor temperature reaches 63.2% of the temperature difference. The value is measured in the air.
Part number
Dimensions
D
T
D
D
M 5R1 07 T3 C
C : Clinch lead
D : Straight lead
CS : Clinch short
Taping
Element diameter : 7
Resistance at 25 C : 5.1
Mark
5R110
1N
5R110
1N
5R110
1N
3.0 min.
H
H
0
3.0 min.
25 min.
25min.
Lead wire 0.8
Soldered copper wire
H
0
d
3.5 0.75
3. Clinch short lead type
UL approved
File No. E92669
Thermistor type devices
d
1. Straight lead type
d
2. Clinch lead type
Taping
P
h
M
...
07
M
...
10
M
...
14
D
9.5max.
13max.
17max.
T
6max.
H
12max.
17max.
20.5max.
H
0
15max.
19.5max.
22.5max.
d
7.5 1
W
W
0
W
2
W
1
P
1
F
1
L
H
1
P
O
D
0
t
1
t
Taping
P
W
P
0
P
1
M
...
07
15 1
M
...
10
15 0.3 3.75 0.7 18
1.0
0.5
...
14 30 1
M
W
0
W
1
W
2
H
1
L
F
1
D
0
t
t
1
h
5min. 9 0.5 3max. 16 0.5 1max. 7.5 0.5 4 0.2 0.6 0.3 1.5max. 0 2
23
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