NTC thermistors for
inrush current limiting
Leaded and coated disks
Series/Type:
Date:
B57238S0***M0**
October 2013
© EPCOS AG 2015. Reproduction, publication and dissemination of this publication, enclosures hereto and the
information contained therein without EPCOS' prior express consent is prohibited.
EPCOS AG is a TDK Group Company.
Inrush current limiters
ICLs
B57238S0***M0**
S238
Applications
Switch-mode power supplies
Soft-start motors, e.g. in vacuum cleaners
Features
Useable in series connections
up to 265 V
RMS
Coated thermistor disk for line applications
Kinked leads of tinned copper wire
Wide resistance range
Manufacturer's logo, NTC and resistance value
stamped on
UL approval (E69802)
Options
Resistance tolerance <20% and alternative lead
configurations available on request
Delivery mode
Bulk (standard) or with cardboard tape on 500-mm reel
General technical data
Climatic category
Max. power
Resistance tolerance
Rated temperature
Dissipation factor
Thermal cooling time constant
Heat capacity
(IEC 60068-1)
(at 25
°C)
Dimensional drawing
Dimensions in mm
Approx. weight 3 g
(in air)
(in air)
P
max
∆R
R
/R
R
T
R
δ
th
τ
c
C
th
55/170/21
3.9
±20
25
approx. 20
approx. 80
approx. 1600
W
%
°C
mW/K
s
mJ/K
Please read
Cautions and warnings
and
Important notes
at the end of this document.
Page 2 of 20
Inrush current limiters
ICLs
B57238S0***M0**
S238
Electrical specification and ordering codes
R
25
Ω
2.5
3
4.7
5
7
8
10
15
16
22
25
I
max
(0...65
°C)
A
8.4
7.4
6.6
6.4
6.0
5.5
5.0
4.4
4.0
4.0
3.4
C
test1)
230 V AC
µF
700
700
700
700
700
700
700
700
700
700
700
C
test1)
110 V AC
µF
2800
2800
2800
2800
2800
2800
2800
2800
2800
2800
2800
R
min
Ordering code
(@ I
max
, 25
°C)
Ω
0.054
0.068
0.090
0.097
0.113
0.131
0.160
0.210
0.246
0.257
0.339
B57238S0259M0**
B57238S0309M0**
B57238S0479M0**
B57238S0509M0**
B57238S0709M0**
B57238S0809M0**
B57238S0100M0**
B57238S0150M0**
B57238S0160M0**
B57238S0220M0**
B57238S0250M0**
** = Delivery mode
00 = Bulk
51 = Reel packing
1) For details on the capacitance C
test
please refer to "Application notes", chapter 1.6.
Please read
Cautions and warnings
and
Important notes
at the end of this document.
Page 3 of 20
Inrush current limiters
ICLs
B57238S0***M0**
S238
Reliability data
Test
Storage in
dry heat
Standard
IEC
60068-2-2
Test conditions
∆R
25
/R
25
(typical)
< 20%
Remarks
No visible
damage
Storage in damp
heat, steady state
Thermal schock
Endurance
Cyclic
endurance
Maximum
permissible
capacitance test
Note
Storage at upper
category temperature
T: 170
°C
t: 1000 h
IEC
Temperature of air: 40
°C
60068-2-78 Relative humidity of air: 93%
Duration: 21 days
IEC
Lower test temperature: 55
°C
60068-2-14 t: 30 min
Upper test temperature: 170
°C
t: 30 min
Time to change from lower to
upper temperature: < 30 s
Number of cycles: 10
IEC
Ambient temperature: 25
±5 °C
60539-1
I = I
max
t: 1000 h
IEC
Ambient temperature: 25
±5 °C
60539-1
I = I
max
On-time = 1 min
Cooling time = 5 min
Number of cycles: 1000
IEC
Ambient temperature: 25
±5 °C
60539-1
Capacitance = C
test
Number of cycles: 1000
< 20%
No visible
damage
No visible
damage
< 20%
< 20%
No visible
damage
No visible
damage
< 20%
< 20%
No visible
damage
The self-heating of a thermistor during operation depends on the load applied and the
applicable dissipation factor.
When loaded with maximum allowable current/power and the specified dissipation factor is
taken as a basis, the NTC thermistor may reach a mean temperature of up to 250
°C.
The heat developed during operation will also be dissipated through the lead wires. So the
contact areas, too, may become quite hot at maximum load.
When mounting NTC thermistors you have to ensure that there is an adequate distance
between the thermistor and all parts which are sensitive to heat or combustible.
Please read
Cautions and warnings
and
Important notes
at the end of this document.
Page 4 of 20
Inrush current limiters
ICLs
B57238S0***M0**
S238
Resistance versus temperature
S238 series
Please read
Cautions and warnings
and
Important notes
at the end of this document.
Page 5 of 20
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