WW/MWW/NWW Series
General Purpose and Precision Wirewound Resistor
Features:
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•
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•
•
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Stackpole Electronics, Inc.
Resistive Product Solutions
WWS offers miniature size at higher power rating
High performance for low cost
High power to size ratio
MWW – completely molded construction with welded terminations
Complete welded terminations
Tinned copper leads
Available in non-inductive styles
High temperature silicone coating
RoHS compliant
Higher operating temperatures may be available. Contact factory.
Electrical Specifications
Type / Code
MIL-R-26 Ref.
Dielectric
Strength
(V)
500V
500V
500V
1,000V
500V
1,000V
1,000V
1,000V
1,000V
1,000V
1,000V
1,000V
1,000V
1,000V
1,000V
1,000V
1,000V
1,000V
1,000V
1,000V
1,000V
1,000V
Power Rating
(Watts)
@ 25ºC
0.4W
1W
1W
1.5W
2.5W
2.5W
3W
3W
3W
4W
4W
5W
5W
6.5W
6.5W
7W
10W
10W
1W
3W
5W
10W
Resitance Temperature
Coefficient
Ohmic Range(Ω) and Tolerance(1)
0.1%, 0.5%, 1% & 5%
Standard
0.1 - 2K
0.1 - 3K
0.1 - 7K
0.1 - 10K
0.1 - 3K
0.1 - 15K
0.1 - 22K
0.1 - 10K
0.1 - 30K
0.1 - 40K
0.1 - 22K
0.1 - 50K
0.1 - 40K
0.1 - 70K
0.1 - 50K
0.1 - 100K
0.1 - 150K
0.1 - 100K
0.1 - 2K
0.1 - 20K
0.1 - 40K
0.1 - 150K
Non-Inductive
0.1 - 1K
0.1 - 1.5K
0.1 - 3.5K
0.1 - 5K
0.1 - 1.5K
0.1 - 7.5K
0.1 - 11K
0.1 - 5K
0.1 - 15K
0.1 - 20K
0.1 - 11K
0.1 - 25K
0.1 - 20K
0.1 - 35K
0.1 - 25K
0.1 - 50K
0.1 - 75K
0.1 - 50K
-
-
-
-
(N)WWH
-
(N)WW1
-
(N)WW1A
RW-70
(N)WW2
RW-69
(N)WWS2
-
(N)WW2A
-
(N)WW3
RW-79
(N)WWS3
RW-69
(N)WW3A
-
(N)WW4
-
(N)WWS4
RW-79
(N)WW5
RW-67, RW-74
(N)WWS5
-
(N)WW7
-
(N)WWS7
RW-67, RW-74
(N)WW7B
-
(N)WW10
RW-78
(N)WWS10
-
(N)MWW1
RW-70
(N)MWW3
RW-79
(N)MWW5
RW-67, RW-74
(N)MWW10
RW-68, RW-74
(1) Lesser of√PR or maximum working voltage
< 1Ω = ±90ppm/ºC
1Ω to 10Ω = ±50ppmºC
>10Ω = ±20ppm/ºC
Please refer to the High Power Resistor Application Note (page 4) for more information on designing and
implementing high power resistor types.
Rev Date: 08/11/2011
This specification may be changed at any time without prior notice
Please confirm technical specifications before you order and/or use.
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WW/MWW/NWW Series
General Purpose and Precision Wirewound Resistor
Stackpole Electronics, Inc.
Resistive Product Solutions
Mechanical Specifications
Type / Code
(N)WWH
(N)WW1 / (N)WWS2
(N)WW1A
(N)WW2 / (N)WWS3
(N)WW2A
(N)WW3 / (N)WWS4
(N)WW3A
(N)WW4 / (N)WWS5
(N)WW5 / (N)WWS7
(N)WW7
(N)WW7B / (N)WWS10
(N)WW10
(N)MWW1
(N)MWW3
(N)MWW5
(N)MWW10
A
0.312 ± 0.062
7.9 ± 1.6
0.375 ± 0.062
9.5 ± 1.6
0.42 ± 0.062
10.7 ± 1.6
0.37 ± 0.062
9.4 ± 1.6
0.55 ± 0.062
14 ± 1.6
0.56 ± 0.062
14.2 ± 1.6
0.5 ± 0.062
12.7 ± 1.6
0.7 ± 0.062
17.8 ± 1.6
0.875 ± 0.062
22.2 ± 1.6
1 ± 0.062
25.4 ± 1.6
1.2 ± 0.062
30.5 ± 1.6
1.78 ± 0.062
45.2 ± 1.6
0.385 ± 0.062
9.8 ± 1.6
0.56 ± 0.062
14.2 ± 1.6
0.925 ± 0.062
23.5 ± 1.6
1.965 ± 0.062
49.9 ± 1.6
B
0.11 ± 0.031
2.8 ± 0.8
0.11 ± 0.031
2.8 ± 0.8
0.11 ± 0.031
2.8 ± 0.8
0.156 ± 0.031
4 ± 0.8
0.156 ± 0.031
4 ± 0.8
0.187 ± 0.031
4.8 ± 0.8
0.218 ± 0.031
5.5 ± 0.8
0.27 ± 0.031
6.9 ± 0.8
0.312 ± 0.031
7.9 ± 0.8
0.312 ± 0.031
7.9 ± 0.8
0.312 ± 0.031
7.9 ± 0.8
0.375 ± 0.031
9.5 ± 0.8
0.135 ± 0.031
3.4 ± 0.8
0.205 ± 0.031
5.2 ± 0.8
0.33 ± 0.031
8.4 ± 0.8
0.48 ± 0.031
12.2 ± 0.8
C
0.025 ± 0.002
0.64 ± 0.05
0.025 ± 0.002
0.64 ± 0.05
0.025 ± 0.002
0.64 ± 0.05
0.032 ± 0.002
0.81 ± 0.05
0.032 ± 0.002
0.81 ± 0.05
0.032 ± 0.002
0.81 ± 0.05
0.032 ± 0.002
0.81 ± 0.05
0.036 ± 0.002
0.91 ± 0.05
0.036 ± 0.002
0.91 ± 0.05
0.036 ± 0.002
0.91 ± 0.05
0.036 ± 0.002
0.91 ± 0.05
0.036 ± 0.002(1)
0.91 ± 0.05(1)
0.032 ± 0.002
0.81 ± 0.05
0.032 ± 0.002
0.81 ± 0.05
0.036 ± 0.002
0.91 ± 0.05
0.04 ± 0.002
1.02 ± 0.05
Unit
inches
mm
inches
mm
inches
mm
inches
mm
inches
mm
inches
mm
inches
mm
inches
mm
inches
mm
inches
mm
inches
mm
inches
mm
inches
mm
inches
mm
inches
mm
inches
mm
(1) Available in 0.04mm / 0.0016"
Performance Characteristics
Test
Moisture Resistance
Load Life
Temperature Cycling
Short Time Overload
Test Condition
1000 hours, 95% R.H., 40ºC
1000 hours,
cycled power 1.5 hours ON, 0.5 hours OFF, 25ºC
5 cycles, -55ºC to 200ºC
5 times rated power for 5 seconds
Result
1% max
1%
0.5%
1%
Rev Date: 08/11/2011
This specification may be changed at any time without prior notice
Please confirm technical specifications before you order and/or use.
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WW/MWW/NWW Series
General Purpose and Precision Wirewound Resistor
Power Derating Curve:
Percent Rated Power (%)
120
100
80
60
40
20
Stackpole Electronics, Inc.
Resistive Product Solutions
25
75
125
175
225
275
325
350
Ambient Temperature (ºC)
Operating Temperature Range: -25ºC to +350ºC
How to Order
1
2
3
4
5
6
7
8
9
W
W
1
F
T
1
K
0
0
Product Series
Standard
WW
Mini
WWS
Molded
MWW
Non-Inductive
NWW
Mini
NWWS
Non-Inductive
Type/Code
(N)WWH
(N)WW1
(N)WW1A
(N)WW2
(N)WWS2
(N)WW2A
(N)WW3
(N)WWS3
(N)WW3A
(N)WW4
(N)WWS4
(N)WW5
(N)WWS5
(N)WW7
(N)WWS7
(N)WW7B
(N)WW10
(N)WWS10
(N)MWW1
(N)MWW3
(N)MWW5
(N)MWW10
Power Rating
@ 25ºC
0.4W
1W
1W
1.5W
2.5W
2.5W
3W
3W
3W
4W
4W
5W
5W
6.5W
6.5W
7W
10W
10W
1W
3W
5W
10W
Tolerance
Tol
Code
0.1%
B
0.5%
D
1%
F
5%
J
Code Description
Size
(N)WWH, (N)WW1, (N)WWS2,
(N)WW1A, (N)MWW1
(N)WW2, (N)WWS3, (N)WW2A,
(N)WW3, (N)WWS4, (N)MWW3
(N)WW3A, (N)WW4, (N)WWS5
(N)WW5, (N)WWS7, (N)WW7,
(N)WW7B, (N)WWS10,
(N)MWW5
(N)WW10, (N)MWW10
Quantity
2,500
2,000
Resistance Value
Four characters with
the multiplier used as
the decimal holder.
0.1 ohm = R100
2 Kohm = 2K00
T
11" reel
tape
500
250
Legacy Part Number (before January 3, 2011):
SEI Type
Code
Nominal
Resistance
Tolerance
Packaging
WW
Type
WW
WWS
MWW
NWW
NWWS
Description
Standard
Mini
Molded
Non-Inductive
Mini
Non-Inductive
1
10K
1%
Tolerance
0.1%
0.5%
1%
5%
R
Types
(N)WWH, (N)WW1, (N)WWS2, (N)WW1A, (N)MWW1
(N)WW2, (N)WWS3, (N)WW2A, (N)WW3,
(N)WWS4, (N)MWW3
(N)WW3A, (N)WW4, (N)WWS5, (N)WW5,
(N)WWS7, (N)WW7, (N)WW7B,
(N)WWS10, (N)MWW5
(N)WW10, (N)MWW10
Qty
2,500
2,000
500
250
11" reel
tape
R
Description
Code
Rev Date: 08/11/2011
This specification may be changed at any time without prior notice
Please confirm technical specifications before you order and/or use.
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marketing@seielect.com
WW/MWW/NWW Series
General Purpose and Precision Wirewound Resistor
Stackpole Electronics, Inc.
Resistive Product Solutions
High Power Chip Resistors and Thermal Management
Stackpole has developed several surface mount resistor series in addition to our current sense resistors,
which have had higher power ratings than standard resistor chips. This has caused some uncertainty and
even confusion by users as to how to reliably use these resistors at the higher power ratings in their designs.
The data sheets for the RHC, RMCP, RNCP, CSR, CSRN, CSRF, CSS, and CSSH state that the rated
power assumes an ambient temperature of no more than 100 degrees C for the CSS / CSSH series and 70
degrees C for all other high power resistor series. In addition, IPC and UL best practices dictate that the
combined temperature on any resistor due to power dissipated and ambient air shall be no more than 105C.
At first glance this wouldn’t seem too difficult, however the graph below shows typical heat rise for the CSR
½ 100 milliohm at full rated power. The heat rise for the RMCP and RNCP would be similar. The RHC with
its unique materials, design, and processes would have less heat rise and therefore would be easier to
implement for any given customer.
The 102 degrees C heat rise shown here would indicate there will be additional thermal reduction techniques
needed to keep this part under 105C total hot spot temperature if this part is to be used at 0.75 watts of
power. However, this same part at the usual power rating for this size would have a heat rise of around 72
degrees C. This additional heat rise may be dealt with using wider conductor traces, larger solder pads and
land patterns under the solder mask, heavier copper in the conductors, vias through PCB, air movement, and
heat sinks, among many other techniques. Because of the variety of methods customers can use to lower
the effective heat rise of the circuit, resistor manufacturers simply specify power ratings with the limitations
on ambient air temperature and total hot spot temperatures and leave the details of how to best accomplish
this to the design engineers. Design guidelines for products in various market segments can vary widely so it
would be unnecessarily constraining for a resistor manufacturer to recommend the use of any of these
methods over another.
Note:
The final resistance value can be affected by the board layout and assembly process, especially the size of the
mounting pads and the amount of solder used. This is especially notable for resistance values
≤
50 mΩ.
This should be taken into account when designing.
Rev Date: 08/11/2011
This specification may be changed at any time without prior notice
Please confirm technical specifications before you order and/or use.
4
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