Approval sheet
WW25X, WW18X, WW12X, WW08X,
WW06X
±
1%,
±
5%
Thick Film Current Sensing Chip Resistors
Size 2512, 1218, 1206, 0805, 0603
(Automotive)
*Contents in this sheet are subject to change without prior notice.
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ASC_WW25-18-12-08-06X_J_AUTO_V02
Nov. - 2012
Approval sheet
FEATURE
1.
2.
3.
4.
High power rating and compact size
Automotive AEC Q-200 Compliant
100% CCD Visual inspection
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 a lead free tin alloy.
Fig 1. Construction of 2512, 1206, 0805, 0603 Chip-R
Fig 2. Construction of a 1218 Chip-R
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ASC_WW25-18-12-08-06X_J_AUTO_V02
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Approval sheet
QUICK REFERENCE DATA
Item
Series No.
Size code
Resistance Tolerance
WW25X
2512 ( 6432 )
WW18X
1218 (3248)
General Specification
WW12X
1206 (3216)
±5%, ±1%
(E24+E96)
Resistance Range
TCR (ppm/°C)
0.02Ω
≤
Rn < 0.05Ω
0.05Ω
≤
Rn < 0.10Ω
0.10Ω
≤
Rn < 0.50Ω
0.50Ω
≤
Rn < 1Ω
Max. dissipation at
T
amb
=70°C
Max. Operation Current
(DC or RMS)
Max. Overload Current
(DC or RMS)
Operation Temperature
≤
2100 ppm/°C
≤
1000 ppm/°C
≤
500 ppm/°C
≤
400 ppm/°C
1W
7.07 ~ 1.01A
14.14 ~ 2.02A
-55/+155’C
≤
1500 ppm/°C
≤
1000 ppm/°C
≤
500 ppm/°C
≤
300 ppm/°C
1W
7.07 ~ 1.01A
14.14 ~ 2.02A
-55/+155’C
≤
2100 ppm/°C
≤
1000 ppm/°C
≤
500 ppm/°C
≤
400 ppm/°C
1/4 W
3.53 ~ 0.50A
7.06 ~ 1.0A
-55/+155’C
≤
1500 ppm/°C
≤
1000 ppm/°C
≤
500 ppm/°C
≤
300 ppm/°C
1/8 W
2.50 ~ 0.35A
5.00 ~ 0.70A
-55/+155’C
≤
500 ppm/°C
≤
300 ppm/°C
1/10W
1.0 ~ 0.3A
2.0 ~ 0.6A
-55/+155’C
0.02Ω ~ 0.976Ω
0.02Ω ~ 0.976Ω
0.02Ω ~ 0.976Ω
0.02Ω ~ 0.976Ω
0.1Ω ~ 0.976Ω
WW08X
0805 (2012)
WW06X
0603 (1608)
MECHANICAL DATA (unit : mm)
Dimension
L
W
T
Tt
Tb
WW25
6.40±0.20
3.20±0.20
0.60±0.10
0.65±0.25
0.90±0.25
WW18
3.05±0.15
4.60±0.20
0.55±0.10
0.45±0.25
0.50±0.25
WW12
3.10
±
0.10
1.60
±
0.10
0.60
±
0.15
0.50
±
0.20
0.45
±
0.20
WW08
2.00
±
0.10
1.25
±
0.10
0.50
±
0.15
0.40
±
0.20
0.40
±
0.20
WW06
1.60
±
0.10
0.80
±
0.10
0.45
±
0.15
0.30
±
0.10
0.30
±
0.20
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ASC_WW25-18-12-08-06X_J_AUTO_V02
Nov. - 2012
Approval sheet
MARKING
For 0805 and above sizes, each resistor is marked with a four-digit code on the protective coating to
designate the nominal resistance value.
Example:
R010 = 0.01Ω
R510 = 0.51Ω
For 0603 size, each resistor is marked with a three-digit code on the protective coating to designate the
nominal resistance value.
Example:
R10 = 0.10Ω
R51 = 0.51Ω
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.3
Fig 3. Max. 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_WW25-18-12-08-06X_J_AUTO_V02
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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 4.
Fig 4. Infrared soldering profile for Chip Resistors
CATALOGUE NUMBERS
The resistors have a catalogue number starting with .
WW25
Size code
WW25 : 2512
WW18 : 1218
WW12 : 1206
WW08 : 0805
WW06 : 0603
X
Type code
X : Normal
R020
Resistance code
E96 +E24:
R is first digit followed by
3 significant digits.
0.020Ω = R020
0.510Ω = R510
0.025Ω = R025
J
Tolerance
J :
±5%
F :
±1%
T
Packaging
code
T : Reeled
L
Termination
code
L
=
Sn base
(lead free)
J
Special code
J =
Automotive grade
AEC Q-200 compliant,
100% CCD visual
inspection
Page 5 of 8
ASC_WW25-18-12-08-06X_J_AUTO_V02
Nov. - 2012
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