MAR40

Ultra Precision Metal Film Resistors MAR 40/42 series Welwyn Components • Tolerance down to 0.005% • Very low TCRs • Rugged moulded protection • Matched sets available Electrical Data Notes Power rating at 85°C Resistance range Limiting element voltage TCR (0°C to +60°C) TCR (-55°C to +125°C) Resistance tolerance Standard values Thermal impedance Ambient temperature range °C/watt °C watts ohms volts ppm/°C ppm/°C % 0.3 20R0 to 400K 250 2 (T18) & 5 (T16) 5 (T18) & 10 (T16) 0.005, 0.01, 0.02, 0.05, 0.1, 0.25, 0.5 & 1 E24, E96 preferred 80 - 55 to +155 Any value to order Higher values by agreement Physical Data Dimensions (mm) and Weight (g) Type MAR 40 MAR 42 L max. 7.75 8.25 H max. 8.64 8.64 W max. 3.3 3.3 T min. 25.4 25.4 d nom. 0.6 0.6 S nom. 3.8 5.1 Wt. nom. 0.65 0.65 H L W T S d Construction Ceramic rods are coated with a metal film and plated steel caps are force fitted. A helical cut is used to adjust the film to its final value. Termination wires are welded to the caps and the resistor is protected with a multiple lacquer coat and encapsulated in an epoxy moulded protection. Marking Type reference, TCR code, resistance value and tolerance. The resistance value marking conforms to IEC 62. Solvent Resistance The body protection and marking are resistant to all normal industrial cleaning fluids suitable for printed circuits. Terminations Material Strength Solderability Solder-coated copper wire. The terminations meet requirements of IEC 68.2.21 and MIL-STD 1276. The terminations meet the requirements of IEC 115-1, Clause 4.17.3.2 and MIL-STD 202. 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 Issue B · 03.02 © Welwyn Components Limited · Bedlington, Northumberland NE22 7AA, UK Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com 180 Ultra Precision Metal Film Resistors MAR 40/42 series Welwyn Components Performance Data Test conditions per MIL-R55182 except where noted Maximum Load at rated power: 1000 hrs at 85°C Dry heat: 1000 hrs at 155°c Shelf life: 12 months at room temperature Derating from rated power at 85°c Short term overload Damp heat (IEC 68-2-3) Effect of solder (tested per method 210, MIL-STD 202) Vibration and bump Noise (in a decade of frequency) Voltage coefficient of resistance ∆R% ∆R% ∆R% ∆R% µV/V ppm/V 0.01 0.04 0.04 0.02 0.02 0.1 0.2 ∆R% ∆R% ∆R% 0.05 0.10 0.01 Zero at 155°C 0.001 0.02 0.01 0.003 0.002 0.03