Cement Coated Surface
Mount Wirewound Resistors
CSM Series
Welwyn Components
•
•
•
•
•
•
All welded construction
Suitable for automatic pick and place
Excellent pulse handling capability
Fuses safely under fault conditions
Competitive cost
Meets the requirements of EN 140402-801
Electrical Data
CSM2
Power rating at 25˚C
Resistance range
Limiting element voltage
TCR
Resistance tolerance
Standard values
Ambient temperature range
°C
watts
ohms
volts
ppm/°C
%
2
0R05 to 900R
50
<0R1: 200, <10R: 150,
≥10R:
100
<1R: 5, 10
≥1R:
1, 2, 5, 10
CSM3
3
0R01 to 3K0
100
0R01: 1000, <0R03: 500, <0R1: 200,
<10R: 150,
≥10R:
100
<0R1: 5, 10
-55 to 155
≥0R1:
1, 2, 5, 10
E24 series preferred
Physical Data
Dimensions (mm)
Type
CSM2
L
12.0±0.3
W
3.6 max
H
5.0 max
l
9.0 max
w
3.0±0.3
b
3.0±0.3
W
I
L
w
Max +5˚
Min -0˚
CSM3
17.7±0.3
5.6 max
6.5 max
13.0 max
3.0±0.3
3.5±0.3
H
b
b
Recommended Pad Sizes
Dimensions (mm)
Type
CSM2
CSM3
A
3.4
3.4
B
4.0
4.5
C
6.0
11.0
D
14.0
20.0
B
A
C
D
Construction
A high purity ceramic substrate is assembled with interference
fit end-caps to which are welded the terminations. The
resistive element is wound on the substrate and welded to
the caps. Flameproof silicone cement coating is applied prior
to lead forming and marking.
General Note
Welwyn Components reserves the right to make changes in product specification without notice or liability.
All information is subject to Welwyn’s own data and is considered accurate at time of going to print.
A subsidiary of
TT electronics plc
Issue H · 06.02
© Welwyn Components Limited
· Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
Cement Coated Surface
Mount Wirewound Resistors
CSM Series
Marking
CSM resistors are marked with value and tolerance. They can
be either legend or band marked (using four colour bands),
depending on batch size. Where they are legend marked, on
the CSM2, the tolerance is indicated by a code letter (see
Ordering Information for codes.)
Welwyn Components
Solvent Resistance
The body protection and marking are resistant to all normal
industrial cleaning solvents suitable for printed circuits.
Flammability
The resistor coating will not burn under any condition of
applied temperature or component overload.
Performance Data
Load at Rated Power: 1000hrs @ 25°C
Dry heat: 1000hrs @ 155°C
Short term overload: 6.25 x Rated Power for 5 Seconds
Derating from Rated Power @ 25°C
Climatic
Climatic category
Temperature rapid change: -55/155°C
Resistance to solder heat: 260°C for 10S
Isolation voltage
Temperature rise
Pulse handling
∆R%
∆R%
∆R%
∆R%
∆R%
∆R%
V
CSM2
CSM3
2 +0.001Ω
3 +0.001Ω
2 +0.001Ω
3 +0.001Ω
1 +0.001Ω
2 +0.001Ω
Zero at 155˚C
1 +0.001Ω
55/155/56
1 +0.001Ω
1 +0.001Ω
250
500
See Graph 1
See Graph 2
EN 140402-801
2 +0.05Ω
2 +0.05Ω
2 +0.05Ω
2 +0.05Ω
2 +0.05Ω
2 +0.05Ω
Note: Testing was performed on FR4 test boards measuring 50mm x 50mm, with 1oz/ft
2
(300g/m
2
) copper pads. The track area
close to each pad was 120mm
2
. If a lower grade of PCB or less track area is used, derating of the power may be necessary.
Temperature Rise
Graph 1
220
200
180
160
CSM Thermal Performance
Temp Rise (C)
140
120
100
80
60
40
20
0
0
0.5
1
1.5
2
2.5
3
Power (W)
CSM Hot Spot
CSM3 Joint
CSM2 Hot Spot
CSM2 Joint
© Welwyn Components Limited
Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
Issue H · 06.02
Cement Coated Surface
Mount Wirewound Resistors
CSM Series
Welwyn Components
Pulse Handling
The graph below shows the energy handling capability of
CSM resistors for single short pulses (<100mS). For longer
pulses of duration up to 5 Seconds, up to 5 times the rated
power may be applied. Note that forced-air cooling and
heatsinking by PCB tracks have no effect on energy ratings. If
higher energy ratings than those shown are needed, it is
normally possible to design a pulse withstand variant.
Graph 2
100
CSM Energy Capability Graph
Energy (Joules)
10
1
0.1
0.01
0.1
1
10
Value (ohms)
CSM2
CSM3
100
1000
10000
Packaging
CSM products are supply on standard carrier tape and
330mm diameter reels suitable for automatic pick and place
machines. Carrier tape dimensions and standard reels
quantities are given below.
Ordering Procedure
Specify type reference, value and tolerance as shown in this
example of CSM3 at 1.5KOhms, 5%:
Dimensions (mm)
Type
CSM2
CSM3
Ao
3.4
4.65
Bo
12.7
18.3
Ko
5.3
6.7
W
24
32
P
8
12
T
0.4
0.4
Quantity
per reel
1250
750
ø 13mm
Type
Value (use IEC 62 code)
Tolerance (use IEC 62 code)
F
G
J
K
1%
2%
5%
10%
CSM3
1K5
J
Ao
Bo
P
W
Ko
ø 330mm
All other dimensions as
per EIA481 standard
24mm / 32mm
© Welwyn Components Limited
Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
Issue H · 06.02
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