Moulded Surface Mount
Wirewound Resistors
Welwyn Components
WSM Series
• Ideal for automatic pick and place
• Direct replacement for Axial resistors
• All welded construction
Electrical Data
WSM1
1
WSM2
2
WSM3
3
Power rating at 70°C
Resistance range
Limiting element voltage
TCR
watts
ohms
0R01 to 1K
0R01 to 2K
100
0R01 to 3K
volts
ppm/°C
< 1 Ω : 100
≥ 1 Ω : 20
< 1 Ω : 100
≥ 1 Ω : 20
*1, 2, 5, 10
E24 preferred
-55 to 155
≤.03 Ω 700 ≤0.1 Ω : 200
≤10R 100 >10R 20
Resistance tolerance
Standard values
%
°C
Ambient temperature range
*Note 5% or 10% preferred below 0.1 ohms
Physical Data
Dimensions (mm)
L
W
Type
L max
7.9
I Nom
2.54
3.1
W Max
7
w Max
4.2
H Max
3.94
5.5
w
WSM1
WSM2
WSM3
I
H
12
10.5
16
6.6
18
3.1
7
6.5
Recommended Pad Sizes
Type
A
B
C
2.8
6
D
B
C
D
WSM1
WSM2
WSM3
2.9
3.4
3.4
2.6
4.0
4.5
8.1
14
20
A
11
Construction
Marking
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. The unit is then moulded.
WSM resistors are legend marked with type value and
tolerance.
WSM1 Resistors are marked with value and tolerance.
Solvent Resistance
The body protection and marking are resistant to all normal
Flammability
The resistor coating is a flame retardant epoxy to UL 94.
industrial cleaning solvents suitable for printed circuits.
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
© 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 C · 04.03
45
