Approval sheet
WW25P, WW20P, WW12P
±
1%,
±
5% 47m ~976m
High Power Low Ohm Chip Resistors
Size 2512 2W, 2010 1W, 1206 1/2W
*Contents in this sheet are subject to change without prior notice.
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ASC_WW25P-20P-12P_V08
Sep.2010
Approval sheet
FEATURE
1.
2.
3.
4.
High power rating and compact size
High reliability and stability
Reduced size of final equipment
RoHS compliant and lead free products.
APPLICATION
•
•
•
•
•
•
•
Power supply
PDA
Digital meter
Computer
Automotives
Battery charger
DC-DC power converter
DESCRIPTION
The resistors are constructed in a high grade ceramic body (aluminum oxide). Internal metal electrodes are
added at each end and connected by a resistive paste that is applied to the top surface of the substrate.
The composition of the paste is adjusted to give the approximate resistance required and the value is trimmed to
nominated value within tolerance which controlled by laser trimming of this resistive layer.
The resistive layer is covered with a protective coat. Finally, the two external end terminations are added.
For ease of soldering the outer layer of these end terminations is Tin (lead free) alloy.
Fig 1. Consctruction of Chip-R
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ASC_WW25P-20P-12P_V08
Sep.2010
Approval sheet
QUICK REFERENCE DATA
Item
Series No.
Size code
Resistance Tolerance
Resistance Range
TCR (ppm/°C)
100mohm ~ 976mohm
47mohm ~ 97.6mohm
±100ppm
±150ppm
2W
300V
500V
WW25P
2512 (6432)
General Specification
WW20P
2010 (5025)
±1%, ±5%
0.047Ω ~ 0.976Ω
±100ppm
±150ppm
1W
200V
400V
55/155/56
±100ppm
±200ppm
1/2 W
200V
400V
WW12P
1206 (3216)
Max. dissipation at T
amb
=70°C
Max. Operation Voltage (DC or RMS)
Max. Overload Voltage (DC or RMS)
Climatic category (IEC 60068)
Note :
1.
2.
This is the maximum voltage that may be continuously supplied to the resistor element, see “IEC publication
60115-8”
Max. Operation Voltage : So called RCWV (Rated Continuous Working Voltage) is determined by
RCWV
=
Rated Power
×
Resistance Value
or Max. RCWV listed above, whichever is lower.
3.
4.
2W loading with total solder-pad and trace size of 300 mm
2
Resistance value will be changed by soldering condition and design of soldering pad, please design products in
consideration of this change of resistance value.
MECHANICAL DATA
Unit: mm
Symbol
L
W
T
Tt
Tb
WW25P
6.30
±
0.20
3.10
±
0.20
0.60
±
0.15
0.60
±
0.25
1.80
±
0.25
WW20P
5.00
±
0.20
2.50
±
0.20
0.60
±
0.10
0.60
±
0.25
0.60
±
0.25
WW12P
3.10
±
0.15
1.60
±
0.15
0.55
±
0.10
0.50
±
0.25
0.50
±
0.25
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ASC_WW25P-20P-12P_V08
Sep.2010
Approval sheet
Recommended Solder Pad Dimensions
D
W
Type
WW25P
W
3.7mm
D
2.45mm
L
7.6mm
L
MARKING
Each resistor is marked with a four-digit code on the protective coating to designate the nominal resistance
value.
Example:
R100 = 0.100Ω
R910 = 0.910Ω
FUNCTIONAL DESCRIPTION
Product characterization
Standard values of nominal resistance are taken from the E96 & E24 series for resistors with a tolerance of
±5%
&
±1%.
The values of the E24/E96 series are in accordance with “IEC publication 60063”.
Derating curve
The power that the resistor can dissipate depends on the operating temperature; see Fig.2
Figure 2
Maximum dissipation in percentage of rated power as a
function of the ambient temperature
MOUNTING
Due to their rectangular shapes and small tolerances, Surface Mountable Resistors are suitable for handling by
automatic placement systems.
Chip placement can be on ceramic substrates and printed-circuit boards (PCBs).
Electrical connection to the circuit is by individual soldering condition.
The end terminations guarantee a reliable contact.
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ASC_WW25P-20P-12P_V08
Sep.2010
Approval sheet
SOLDERING CONDITION
The robust construction of chip resistors allows
them to be completely immersed in a solder bath
of 260°C for 10 seconds. Therefore, it is possible
to mount Surface Mount Resistors on one side of
a PCB and other discrete components on the
reverse (mixed PCBs).
Surface Mount Resistors are tested for
solderability at 235°C during 2 seconds. The test
condition for no leaching is 260°C for 30 seconds.
Typical examples of soldering processes that
provide reliable joints without any damage are
given in Fig 3.
Fig 3. Infrared soldering profile for Chip Resistors
CATALOGUE NUMBERS
The resistors have a catalogue number starting with.
WW25
Size code
WW25 : 2512
WW20 : 2010
WW12 : 1206
P
Type code
P :Power
2512 size=2 watt
2010 size=1 watt
1206 size=0.5 watt
e.g.:
0.1ohm
E96 +E24:
“R”
R100
Resistance code
is first digit followed by 3
significant digits.
=
=
R100
R047
R560
J
Tolerance
J :
±5%
F :
±1%
T
Packaging code
T : 7” Reel taping
L
Termination code
L
=
Sn base (lead
free)
0.047ohm =
0.56ohm
Tape packaging
WW12 : 8mm width paper taping 5,000pcs per reel.
WW25；WW20
:
12mm width plastic taping 4,000pcs per reel.
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ASC_WW25P-20P-12P_V08
Sep.2010
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