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