Welwyn LOB-1 Low resistance metal element resistor Datasheet

Low Resistance Metal
Element Resistors
Welwyn Components
LOB Series
• Ultra low resistance values
(0.005Ω to 0.1Ω)
• Available in 1, 3 and 5 watt rated packages
• Tolerances from ±1% to ±5%
• Inherently non-inductive (≤.02µH at 0.5MHz)
• Low temperature coefficient of resistance
• High stability over life
Electrical Data
LOB-1
LOB-3
Continuous power dissipation at 25°C in free air
watts
1
3
5
Overload power for 5 seconds
watts
5
15
25
volts
√1xR
√3xR
√5xR
°C
175
175
175
Maximum working voltage
Maximum storage temperature
LOB-5
* Power Dissipation - The maximum wattage rating depends upon the amount of heat which can be transferred to the surroundings while not exceeding the maximum element
temperature. Ambient air temperature, velocity of cooling air, thermal resistance of heat and the temperature of surrounding objects will affect this transfer, this must be taken
into account when selecting a resistor.
Physical Data
Dimensions (mm)
contact point
Type
L max.
D max.
f min.
d nom.
C
LOB-1
9.9±0.3
3.6±0.2
38.1±3.2
0.813±0.05
33.27
LOB-3 14.22±0.25 5.33±0.25 34.93±3.18 0.81±0.05
33.27
LOB-5 23.37±0.25 8.38±0.25 31.75±3.18 1.02±0.05
42.42
d
contact point
C
D
L
f
Description
Construction
LOBΩ Series power precision metal element resistors feature
resistance values down to 0.005Ω with virtually no
inductance. Available in 1, 3 and 5 watt rated axial leaded
packages, these resistors are compatible with automatic
insertion equipment.
LOBΩ Series resistors feature tinned copper leads welded
directly to a low temperature coefficient resistance element in
a highly automated proprietary process. The leaded resistor
elements are then encapsulated in a moulding compound.
Applications
•
•
•
Switchmode and linear power supplies.
Automotive current-sensing circuits.
Instrumentation.
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.
A subsidiary of
TT electronics plc
© Welwyn Components Limited · Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com
104
Issue B · 03.02
Low Resistance Metal
Element Resistors
Welwyn Components
LOB Series
Power derating percentage vs
Free air ambient temperature
Temperature coefficient of resistance vs
Resistance value
Temperature Coefficient
of resistance (ppm/°C)
100
Rated Power (%)
90
80
70
60
50
40
30
20
10
400
300
200
100
0
0
0
25
50
75
100
125
150
175
0
25
50
Resistance (ohms x
Ambient Temp (°C)
75
100
10-3)
Test
MIL-STD 202
MAX %∆R*
Unit
Load life (2000 hours)
Method 108
±1%
%∆R
Thermal shock
Method 107
±1%
%∆R
Vibration
Method 204
±0.5%
%∆R
Mechanical shock
Method 213
±0.5%
%∆R
Dielectric strength
Method 301
±0.5%
%∆R
Insulation resistance
Method 302
>1011
ohms
*±0.0005 ohm allowance for test/contact error.
Packaging
Resistors are supplied taped and reeled.
Bulk packaging available.
© Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com
Issue B · 03.02
105
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