Moulded Surface Mount
Wirewound Resistors
WSM Series
FlexibleTerminaons
Allweldedconstrucon
Idealforautomacpickandplace
Leadfree,RoHScompliantconstrucononly
Contactfactoryforohmicvaluesabovepublishedranges
WSM1 WSM2 WSM3
321sttawC°07 ta gnitar rewoP
K3 ot 50R0K1 ot 10R000R4 ot 10R0smhoegnar ecnatsiseR
001stlovegatlov tnemele gnitimiL
1 <C°/mppRCT Ω: 100 < 1 Ω: 100
≤.03 Ω700 ≤0.1 Ω: 200
≥1 Ω: 20 ≥1 Ω: 20
≤10R 100 >10R 20
01 ,5 ,2 ,1*%ecnarelot ecnatsiseR
Standard values E24 preferred
275°C ot 55-
C°egnar erutarepmet tneibmA
Moulded Surface Mount
Wirewound Resistors
WSM Series
•Ideal for automatic pick and place
•Direct replacement for Axial resistors
•All welded construction
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: info@welwyn-tt.com · Website: www.welwyn-tt.com
Electrical Data
Issue C · 04.03
A subsidiary of
TT electronics plc
Welwyn Components
45
Dimensions Inches (mm)
Type L max I Nom A Max W Max H Max
WSM1
WSM2
WSM3
Type
WSM1
WSM2
WSM3
Physical Data
Recommended Pad Sizes
LAW
IH
BC
D
A
Marking
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
industrial cleaning solvents suitable for printed circuits.
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.
Flammability
The resistor coating is a flame retardant epoxy to UL 94.
*Note 1% and 5% preferred. WSM1 available at 5% only below 1R0. WSM2 available at 5% only below 0R05.
0.157 inch
(4.0 mm)
0.157 inch
(4.0 mm)
0.677 max
(17.2 max)
0.425 max
(10.8 max)
0.64 max
(16.3 max)
0.29 max
(7.4 max)
0.195 max
(5.0 max)
0.13 inch
(3.3 mm)
A B C D
0.138 inch
(3.5 mm)
0.35 inches
(8.9 mm)
0.583 inch
(14.8 mm)
0.85 inch
(21.6 mm)
0.074 inch
(1.9 mm)
0.221 inch
(5.6 mm)
0.378 inch
(9.6 mm)
0.181 inch
(4.6 mm)
0.236 inch
(6.2 mm)
0.310 max
(7.9 max)
0.115 max
(2.9 max)
0.137 max
(3.5 max)
0.137 max
(3.5 max)
0.275 max
(7.0 max)
0.165 max
(4.2 max)
0.155 max
(3.94 max)
0.462 max
(11.7 max)
0.260 max
(6.6 max)
0.265 inch
(6.7 max)
Resistors
06.18
General Note
TT Electronics reserves the right to make changes in product specication without notice or liability.
All information is subject to TT Electronics’ own data and is considered accurate at time of going to print.
© TT Electronics plc
www.ttelectronics.com/resistors
BI Technologies IRC Welwyn
AllpartsarePb-freeandcomplywithEUDirecve2011/65/EUamendedby(EU)2015/863(RoHS3)AllpartsarePb-freeandcomplywithEUDirecve2011/65/EUamendedby(EU)2015/863(RoHS3)
Moulded Surface Mount
Wirewound Resistors
WSM Series
Moulded Surface Mount
Wirewound Resistors
WSM Series
© 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
46
Issue C · 04.02
Welwyn Components
Packing Data
Dimensions (mm)
Ao Bo Ko W P t
WSM1 4.2 7.62 4.2 16 8 0.36
WSM2 6.75 11.95 5.22 24 12 0.36
WSM3 7.3 18.3 6.7 32 12 0.4
All other dimensions as per EIA481 standard
WSM1 WSM2 WSM3
Load at rated power: 1000 hrs @ 70°C ∆R% 2 ± 0.001Ω2 ± 0.001Ω3 ± 0.001Ω
Dry heat 1000 hrs @ 155°C ∆R% 2 ± 0.001Ω2 ± 0.001Ω3 ± 0.001Ω
Short term overload ∆100.0± 2%R Ω
C°275 ta orezC°07 @ rewop detar morf gnitareD
Moisture ∆R% 1 ± 0.001Ω1 ± 0.001Ω1.5 ± 0.001Ω
Temperature cycling ∆100.0± 1%R Ω
Resistance to solder heat ∆100.0± 1%R Ω
000,1Vegatlov noitalosI
M0001>smhoecnatsiser noitalusnI
Substrate bend ∆100.0± 2.0%R Ω
Performance Data
Note: The power ratings to be applied depend upon the board used and the ambient temperature.
t pj | ` KèñÇ==OVLQL MP ==N MWP U =~ã==m~ ÖÉ =O
Ordering Procedure
Example: WSM2 at 4.7 ohms and 5% tolerance on a reel of 800 pieces –
W S M 2 – 4 R 7 J I
Type
Value (use IEC62 code)
Tolerance (use IEC62 code)
F
1%
J
5%
G
2%
K
10%
Packing
I Tape
WSM1
1500/reel
Standard
WSM2
800/reel
WSM3
750/reel
06.18
General Note
TT Electronics reserves the right to make changes in product specication without notice or liability.
All information is subject to TT Electronics’ own data and is considered accurate at time of going to print.
© TT Electronics plc
www.ttelectronics.com/resistors
BI Technologies IRC Welwyn
Ordering Procedure
This product has two valid part numbers:
European (Welwyn) Part Number: WSM3-6K8FI(WSM3,6.8 kilohms ±1%, Pb-free)
W
S
M
3
-
6
K
8
F
I
1
2
3
4
USA (IRC) Part Number: WSM36801FLFTR (WSM3, 6.8 kilohms ±1%, Pb-free)
W
S
M
3
6
8
0
1
F
L
F
T
R
1
2
3
4
5
1
2
3
4
Type Value Tolerance Packing & Termination Finish
WSM1
E24 = 3/4 characters
R = ohms
K = kilohms
F = ±1%
I = Standard packing & Pb-free
WSM2
G = ±2%
WSM1
1500/reel (13” 330mm)
WSM3
J= ±5%
WSM2
800/reel (13” 330mm)
K= ±10%
WSM3
750/reel (13” 330mm)
1
2
3
4
5
Type Value Tolerance Termination Finish Packing
WSM1
3 digits + multiplier
R = ohms for values <100 ohms
F = ±1%
LF = Pb-free
TR = Tape & Reel
WSM2
G = ±2%
WSM1
1500/reel (13” 330mm)
WSM3
J= ±5%
WSM2
800/reel (13” 330mm)
K= ±10%
WSM3
750/reel (13” 330mm)
Moulded Surface Mount
Wirewound Resistors
WSM Series
06.18
General Note
TT Electronics reserves the right to make changes in product specication without notice or liability.
All information is subject to TT Electronics’ own data and is considered accurate at time of going to print.
© TT Electronics plc
www.ttelectronics.com/resistors
BI Technologies IRC Welwyn