Surface Mount Sense
Resistors
OARS, OARS-XP, OARSZ Series
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
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.
© TT electronics plc
04.14
· Flexible leads for thermal expansion
· Open-air design reduces PCB heating
· Values down to 1milliohm
· Element TCR ±20ppm/ºC
· Zero-ohm 65A jumper version
· RoHS compliant
Surface Mount Sense Resistors
AO RS, OARS-XP, OARSZ Series
Flexible leads for thermal expansion
Open-air design reduces PCB heating
Values down to 1mΩ
Element TCR ±20ppm/ºC
Zero-ohm 65A jumper version
RoHS compliant
Electrical Data
OARS1/3 OARS-XP
Power rating at 25ºC watts 2 4
Power rating at 85ºC watts 1 2
Resistance range ohms R002 to R050 R001 to R025
Resistance Tolerance % ≤R002: 5, > R002: 1, 5
Standard Values
(Enquire for unlisted values) milliohms 2, 3, 4, 5, 10, 15, 20, 22, 25, 30, 40, 50 1, 2, 2.5, 5, 7.5, 10, 20, 25
Inductance nH <10
Ambient temperature range °C -55 to +160
OARS-1Z Comments
Current rating at 25ºC amps 65
Current rating at 85ºC amps 46
Ambient temperature range °C -55 to +160
Zero-ohm jumper
Physical Data
Dimensions (mm) and recommended solder pads
Type L H T D W a nom. bnom. cnom. dnom.
OARS1/3 >R003, OARS-1Z 3.05
±0.76
OARS1/3 - R003
11.18
±0.38
4.83
±0.76
3.18
±0.38 4.07
OARS1/3 - R002 11.56
±0.38
3.51
±0.76 4.7
±0.76
3.56
±0.38 4.45
9.37 3.07
OARS-XP 10.7 to
12.0*
2.28 to
4.57*
2.36
±0.25
4.83
±0.76
6.35
±0.38 7.24 9.58 3.18
3.23
* Dependent on ohmic value
a
b
d
c
c
07.11
Surface Mount Sense Resistors
AO RS, OARS-XP, OARSZ Series
Flexible leads for thermal expansion
Open-air design reduces PCB heating
Values down to 1mΩ
Element TCR ±20ppm/ºC
Zero-ohm 65A jumper version
RoHS compliant
Electrical Data
OARS1/3 OARS-XP
Power rating at 25ºC watts 2 4
Power rating at 85ºC watts 1 2
Resistance range ohms R002 to R050 R001 to R025
Resistance Tolerance % ≤R002: 5, > R002: 1, 5
Standard Values
(Enquire for unlisted values) milliohms 2, 3, 4, 5, 10, 15, 20, 22, 25, 30, 40, 50 1, 2, 2.5, 5, 7.5, 10, 20, 25
Inductance nH <10
Ambient temperature range °C -55 to +160
OARS-1Z Comments
Current rating at 25ºC amps 65
Current rating at 85ºC amps 46
Ambient temperature range °C -55 to +160
Zero-ohm jumper
Physical Data
Dimensions (mm) and recommended solder pads
Type L H T D W a nom. bnom. cnom. dnom.
OARS1/3 >R003, OARS-1Z 3.05
±0.76
OARS1/3 - R003
11.18
±0.38
4.83
±0.76
3.18
±0.38 4.07
OARS1/3 - R002 11.56
±0.38
3.51
±0.76 4.7
±0.76
3.56
±0.38 4.45
9.37 3.07
OARS-XP 10.7 to
12.0*
2.28 to
4.57*
2.36
±0.25
4.83
±0.76
6.35
±0.38 7.24 9.58 3.18
3.23
* Dependent on ohmic value
a
b
d
c
c
07.11
Electrical Data
OARS3
OARS-XP
Power rating
at 70°Cambient, or 140°C
terminal temperature
watts 2 3 5
Resistance range
ohms
R002 to R015
R001 to R025
Resistance Tolerance
%
≤ R002: 5, > R002: 1, 5
Standard Values
(Enquire for unlisted values) milliohms
2, 3, 4, 5, 10, 15
1, 2, 2.5, 5, 7.5, 10,
20, 25
Inductance
nH
<10
Ambient temperature range
°C
-55 to +160
OARS-1Z
Comments
Current rating at 25°Cambient
amps
65
Zero-ohm jumper
Max residual resistance
milliohms
0.3
Ambient temperature range
°C
-55 to +160
Temperature Derating
OARSZ
OARS1/3/XP
Note: For OARS1/3/XP this relates to power rating, for OARSZ it relates to current rating.
Surface Mount
Sense Resistors
OARS, OARS-XP, OARSZ Series
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
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.
© TT electronics plc
04.14
Surface Mount Sense Resistors
OARS, OARS-XP, OARSZ Series
Performance Data (AEC-Q200)
OARS1/3 <R004 R004 to R015 >R015
OARS-XP <R002 R002 to R007 >R007
TCR (-55 to 125ºC) ppm/ºC 240 40 40
Thermal Shock ∆R% 0.75 0.75 0.75
High Temp. Exposure (125ºC) ∆R% 1.75 0.5 1
Temp. Cycling (-40 to 125ºC) ∆R% 1 1 0.75
Operational Life ∆R% 211
Biased Humidity ∆R% 0.75 0.5 0.5
Mechanical Shock ∆R% 1.5 1 1
Vibration ∆R% 111
Terminal Strength Meets JIS-C-6429
Solvent Resistance Meets MIL-STD-002 Method 215
Solderability Meets J-STD-002 Method B
Note: Temperature rise data are given here for typical mounting conditions. Actual figures depend on PCB copper weight, mounting pad size, track
width and substrate type. Also, the open air format responds better to forced air cooling than chip format resistors. For values below 5 milliohms
allowance should be made for heat generated in the copper tracks themselves. Application-specific guidance is available on request.
Temperature Derating
0
20
40
60
80
100
120
0 25 50 75 100 125 150 175
Am bient Temperature (Deg C)
% of Rated Power
Pulse Energy Rating
0
20
40
60
80
100
120
1 10 100
Value (m illiohm s)
Energy (J)
OARS1/3 OARS-XP
Note: For OARS-1Z the above derating graph may be applied to
the square of the current rating.
Note: This graph relates to single pulses of short duration (≤100ms).
Higher energy limits apply for longer pulses and overloads
Hot Spot Temperature Rise
7.6m m x 7.6mm pads, 2 oz copper on FR4, still air
0
50
100
150
200
250
300
25% 50% 75% 100%
Proportion of Rated Power
Temperature Rise (K)
50 / 25
30 / 15
10 / 5
5 / -
Value in m illiohms
OARS1/3 / OARS-XP
Joint Temperature Rise
7.6mm x 7.6mm pads, 2 oz copper on FR4, still air
0
20
40
60
80
100
25% 50% 75% 100%
Proportion of Rated Power
Temperature Rise (K)
5 / -
10 / 5
30 / 15
50 / 25
Value in milliohms
OARS1/3 / OARS-XP
07.11
Electrical Data
OARS1
OARS3
OARS-XP
Power rating
at 70°Cambient, or 140°C
terminal temperature
watts 2 3 5
Resistance range
ohms
R002 to R050
R002 to R015
R001 to R025
Resistance Tolerance
%
≤ R002: 5, > R002: 1, 5
Standard Values
(Enquire for unlisted values)
milliohms
2, 3, 4, 5, 10, 15, 20,
22, 25, 30, 40, 50
2, 3, 4, 5, 10, 15
1, 2, 2.5, 5, 7.5, 10,
20, 25
Inductance
nH
<10
Ambient temperature range
°C
-55 to +160
OARS-1Z
Comments
Current rating at 25°Cambient
amps
65
Zero-ohm jumper
Max residual resistance
milliohms
0.3
Ambient temperature range
°C
-55 to +160
Temperature Derating
OARSZ
OARS1/3/XP
Note: For OARS1/3/XP this relates to power rating, for OARSZ it relates to current rating.
Surface Mount
Sense Resistors
OARS, OARS-XP, OARSZ Series
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
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.
© TT electronics plc
04.14
Thermal Performance Examples
These thermal images were taken under ambient conditions of still air at 25°C with the components
mounted on horizontal standard test boards as defined below.
JEDEC standard circuit board:
2” (50.8mm) square FR4
2outer power planes, 2 ounce (70μ) Cu
1” (25.4mm) square exposed
2 inner signal planes, 1 ounce (35μ) Cu
(continuous planes)
In contrast to the flat chip format, the OARS format keeps the hot spot thermally distant from the
solder j oints and reduces undesirable heat delivery into the PCB. Further thermal images for other
ohmic values and power dissipations are available on request.
Kelvin (4 Terminal) Mounting
For high precision applications a Kelvin (4
Terminal) mounting method is
recommended. An example to illustrate the
design principle is shown. High current
connections are made to the two pairs of
larger pads, whilst the voltage sense
connections are made to the two smaller
central pads.
OARS1-R005 at 2W
OARSXP-R0025 at 5W
Surface Mount
Sense Resistors
OARS, OARS-XP, OARSZ Series
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
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.
© TT electronics plc
04.14
Surface Mount Sense Resistors
OARS, OARS-XP, OARSZ Series
Flamm
Construction
ability
The resistor will not burn or emit incandescent particles under any condition of applied temperature or overload.
Marking
The parts are legend marked with
Copper terminations are welded to resistance alloy strip which is then formed. Value adjustment is achieved
by control of width, without the need for subsequent abrasion or notch trimming.
Pb-free termination finish is 96% Sn / 4% Ag alloy.
ohmic value and tolerance code.
Packaging Data
Dimensions (mm)
Type A B C D E F G
OARS1/3, OARS-1Z 4.32±0.08 11.7±0.08 8±0.1
OARS-XP-R001 11.94±0.1
OARS-XP >R001 7.21±0.1 11.56±0.1
24±0.3 11.5±0.1 1.75±0.1 12±0.1 4±0.1
07.11
Surface Mount
Sense Resistors
OARS, OARS-XP, OARSZ Series
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
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.
© TT electronics plc
04.14
Ordering Procedure
Ordering Procedure
This product has two valid part numbers:
European (Welwyn) Part Numbers: OARS1-R01JI(OARS1, 10 milliohms ±5%, Pb-free)
OARS-1Z (OARS-1Z, Pb-free)
O
A
R
S
1
-
R
0
1
J
I
1
2
3
4
O
A
R
S
-
1
Z
1
USA (IRC) Part Numbers: OARS1R010JLF (OARS1, 10 milliohms ±5%, Pb-free)
OARS-1ZLF(OARS-1Z, Pb-free)
O
A
R
S
1
R
0
1
0
J
L
F
1
2
3
4
O
A
R
S
-
1
Z
L
F
1
2
1
2
3
4
Type ValueTolerance Termination & Packing
OARS1
3-5 characters
See Electrical Data
R = ohms
F = ±1%
I = Pb-free, Tape & Reel
OARS3
J = ±5%
OARS1, OARS3
1900/reel
OARS-XP
OARS-XP
1200/reel
1
Type
OARS-1Z
No value or tolerance applies. Termination is Pb-free. Packing is Tape & Reel, 1900/reel.
1
2
3
4
Type ValueTolerance Termination & Packing
OARS1
4/5 characters
See Electrical Data
R = ohms
F = ±1%
LF = Pb-free
OARS3
J = ±5%
OARS1, OARS3
1900/reel
OARS-XP
OARS-XP
1200/reel
1
2
Type Termination & Packing
OARS-1Z
No value or tolerance applies.
LF= Pb-free, Tape & Reel, 1900/reel.