WELWYN WSM

WSM_C.qxd
29/4/03
10:38 am
Page 1
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
WSM2
Power rating at 70°C
watts
1
2
3
Resistance range
ohms
0R01 to 1K
0R01 to 2K
0R01 to 3K
< 1 Ω : 100
< 1 Ω : 100
≥ 1 Ω : 20
≥ 1 Ω : 20
Limiting element voltage
volts
TCR
ppm/°C
Resistance tolerance
WSM3
100
%
≤.03 Ω 700 ≤0.1 Ω : 200
≤10R 100
>10R 20
*1, 2, 5, 10
Standard values
E24 preferred
Ambient temperature range
°C
-55 to 155
*Note 5% or 10% preferred below 0.1 ohms
Physical Data
Dimensions (mm)
Type
L max
I Nom
W Max
w Max
H Max
WSM1
7.9
2.54
7
4.2
3.94
WSM2
12
3.1
10.5
6.6
5.5
WSM3
18
3.1
16
7
6.5
L
W
w
I
H
Recommended Pad Sizes
Type
A
B
C
D
WSM1
2.9
2.6
2.8
8.1
WSM2
3.4
4.0
6
14
WSM3
3.4
4.5
11
20
B
C
A
D
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
Flammability
The resistor coating is a flame retardant epoxy to UL 94.
The body protection and marking are resistant to all normal
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.
© Welwyn Components Limited · Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com
A subsidiary of
TT electronics plc
Issue C · 04.03
45
WSM_C.qxd
29/4/03
10:38 am
Page 2
Moulded Surface Mount
Wirewound Resistors
Welwyn Components
WSM Series
Physical Data
Dimensions (mm)
Ao
Bo
Ko
W
P
t
Po
WSM1
4.2
7.62
4.2
16
8
0.36
4 ± 0.1
WSM2
6.75
11.95
5.22
24
12
0.36
4 ± 0.1
WSM3
7.3
18.3
6.7
32
12
0.4
4 ± 0.1
All other dimensions as per EIA481 standard
Performance Data
WSM1
WSM2
WSM3
Load at rated power: 1000 hrs @ 70°C
∆R%
2 ± 0.001Ω
2 ± 0.001Ω
3 ± 0.001Ω
Dry heat
∆R%
2 ± 0.001Ω
2 ± 0.001Ω
3 ± 0.001Ω
1000 hrs @ 155°C
Short term overload
∆R%
2 ± 0.001Ω
Derating from rated power @ 70°C
zero at 155°C
Moisture
∆R%
Temperature cycling
∆R%
1 ± 0.001Ω
Resistance to solder heat
∆R%
1 ± 0.001Ω
Isolation voltage
1 ± 0.001Ω
1 ± 0.001Ω
V
1.5 ± 0.001Ω
1,000
Insulation resistance
ohms
>1000M
Substrate bend
∆R%
0.2 ± 0.001Ω
Note: The power ratings to be applied depend upon the board used and the ambient temperature.
© Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com
46
Issue C · 04.02