Resistors
Moulded Surface Mount
Moulded Surface Mount
Wirewound Resistors
Wirewound Resistors
WSM Series
WSM Series
Welwyn Components
•
Ideal for automatic pick and place
•
Direct replacement for Axial resistors
Flexible Terminations
All welded construction
•
All welded construction
Ideal for automatic pick and place
Lead free, RoHS compliant construction only
Contact factory for ohmic values above published ranges
All parts are Pb-free and comply with EU Directive 2011/65/EU (RoHS2)
Electrical Data
WSM1
Power rating at 70°C
Resistance range
Limiting element voltage
TCR
Resistance tolerance
Standard values
Ambient temperature range
°C
watts
ohms
volts
ppm/°C
%
< 1
Ω
: 100
≥
1
Ω
: 20
1
0R01 to 400R
WSM2
2
0R01 to 1K
100
< 1
Ω
: 100
≥
1
Ω
: 20
*1, 2, 5, 10
E24 preferred
-55 to 275°C
≤.03 Ω
700
≤0.1 Ω
: 200
≤10R
100
>10R 20
WSM3
3
0R05 to 3K
*Note 1% and 5% preferred. WSM1 available at 5% only below 1R0. WSM2 available at 5% only below 0R05.
Physical Data
Dimensions Inches (mm)
Type
WSM1
WSM2
WSM3
L max
0.310 max
(7.9 max)
0.462 max
(11.7 max)
0.677 max
(17.2 max)
I Nom
0.115 max
(2.9 max)
0.137 max
(3.5 max)
0.137 max
(3.5 max)
A Max
0.275 max
(7.0 max)
0.425 max
(10.8 max)
0.64 max
(16.3 max)
W Max
0.165 max
(4.2 max)
0.260 max
(6.6 max)
0.29 max
(7.4 max)
H Max
0.155 max
(3.94 max)
0.195 max
(5.0 max)
0.265 inch
(6.7 max)
L
I
A
W
H
Recommended Pad Sizes
Type
WSM1
WSM2
WSM3
A
0.13 inch
(3.3 mm)
0.157 inch
(4.0 mm)
0.157 inch
(4.0 mm)
B
0.138 inch
(3.5 mm)
0.181 inch
(4.6 mm)
0.236 inch
(6.2 mm)
C
0.074 inch
(1.9 mm)
0.221 inch
(5.6 mm)
0.378 inch
(9.6 mm)
D
0.35 inches
(8.9 mm)
0.583 inch
(14.8 mm)
0.85 inch
(21.6 mm)
A
D
B
C
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. The unit is then moulded.
Marking
WSM resistors are legend marked with type value and
tolerance.
WSM1 Resistors are marked with value and tolerance.
Flammability
The resistor coating is a flame retardant epoxy to UL 94.
General Note
Solvent Resistance
The body protection and marking are resistant to all normal
industrial cleaning solvents suitable for printed circuits.
General Note
is subject to Welwyn’s own data and is considered accurate at time of going to print.
All information
Welwyn Components reserves the right to make changes in product specification without notice or liability.
TT Electronics reserves the right to make changes in product specification without notice or liability.
© Welwyn
subject to TT Electronics’ own
Bedlington, Northumberland
at time of going
All information is
Components Limited
·
data and is considered accurate
NE22 7AA, UK
to print.
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
subsidiary of
BI Technologies IRC
A
Welwyn
TT electronics plc
http://www.ttelectronics.com/resistors
Issue C · 04.03
© TT Electronics plc
04.18
45
Moulded Surface Mount
Moulded Surface Mount
Wirewound Resistors
Wirewound Resistors
WSM Series
WSM Series
Welwyn Components
Packing Data
Dimensions (mm)
Ao
WSM1
WSM2
WSM3
4.2
6.75
7.3
Bo
7.62
11.95
18.3
Ko
4.2
5.22
6.7
W
16
24
32
P
8
12
12
t
0.36
0.36
0.4
All other dimensions as per EIA481 standard
Performance Data
WSM1
Load at rated power: 1000 hrs @ 70°C
Dry heat
Short term overload
Derating from rated power @ 70°C
Moisture
Temperature cycling
Resistance to solder heat
Isolation voltage
Insulation resistance
Substrate bend
∆R%
∆
R%
∆
R%
V
ohms
∆
R%
1 ± 0.001Ω
1000 hrs @ 155°C
∆R%
∆R%
∆
R%
2 ± 0.001Ω
2 ± 0.001Ω
WSM2
2 ± 0.001Ω
2 ± 0.001Ω
2 ± 0.001
Ω
zero at 275°C
1 ± 0.001Ω
1 ± 0.001
Ω
1 ± 0.001
Ω
1,000
>1000M
0.2 ± 0.001
Ω
1.5 ± 0.001Ω
WSM3
3 ± 0.001Ω
3 ± 0.001Ω
Note: The power ratings to be applied depend upon the board used and the ambient temperature.
Ordering Procedure
Example: WSM2 at 4.7 ohms and 5% tolerance on a reel of 800 pieces
–
WSM2
–
4R7J
I
Type
Value (use IEC62 code)
F
G
Tolerance (use IEC62 code)
1%
2%
J
K
5%
10%
Packing
I
Tape
WSM1
WSM2
WSM3
1500/reel
800/reel
750/reel
Standard
General Note
TT Electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT Electronics’ own data and is considered accurate at time of going to print.
BI Technologies IRC Welwyn
http://www.ttelectronics.com/resistors
© 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
© TT Electronics plc
46
Issue C · 04.02
04.18
Moulded Surface Mount
Wirewound Resistors
WSM Series
Ordering Procedure
This product has two valid part numbers:
European (Welwyn) Part Number: WSM3-6K8FI
(WSM3, 6.8 kilohms ±1%, Pb-free)
W
S
1
1
Type
2
Value
M
3
-
6
K
2
8
F
3
3
F = ±1%
G = ±2%
J = ±5%
K = ±10%
I
4
4
I = Standard packing & Pb-free
WSM1 1500/reel (13” 330mm)
WSM2 800/reel (13” 330mm)
WSM3 750/reel (13” 330mm)
Tolerance Packing & Termination Finish
WSM1 E24 = 3/4 characters
WSM2
R = ohms
K = kilohms
WSM3
USA (IRC) Part Number: WSM36801FLFTR
(WSM3, 6.8 kilohms ±1%, Pb-free)
W
S
1
1
Type
2
Value
M
3
6
8
2
0
1
F
3
L
4
3
F = ±1%
G = ±2%
J = ±5%
K = ±10%
F
T
5
4
LF = Pb-free
5
Packing
TR = Tape & Reel
WSM1 1500/reel (13” 330mm)
WSM2 800/reel (13” 330mm)
WSM3 750/reel (13” 330mm)
R
Tolerance Termination Finish
WSM1
3 digits + multiplier
R = ohms for values <100 ohms
WSM2
WSM3
General Note
TT Electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT Electronics’ own data and is considered accurate at time of going to print.
BI Technologies IRC Welwyn
http://www.ttelectronics.com/resistors
© TT Electronics plc
04.18
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