USR UNR 4-4020 • Highest Stability • Nearly Temperature Independent • Minimum Tolerance • Low Capacity and Inductance • Customized Resistor Values SPECIFICATIONS ELEKTRICAL USR 4-4020 Resistance Range : Power Rating : Thermal Resistance Rthj-c : UNR 4-4020 note1) 0R05 ... 500R 0R05 ... 500R other resistance values upon request / power rating depending on resistor value 2.5 W (70°C) without heatsink 30 W* 50 W* * with heatsink 3.6 K/W 2.2 K/W Tolerances from 0R05 from 10R from 50R : : : : 0.1%, 0.25%, 0.5%, 1% 0.05%, 0.1%, 0.25%, 0.5%, 1% 0.01%, 0.02%, 0.05%, 0.1%, 0.25%, 0.5%, 1% Stability : 0.01% Temperature Coefficient : max. ±5 ppm/K (-55...155)°C typ. ±3 ppm/K (-55...125)°C upon request ±1 ppm/K (0...60)°C Voltage Proof Max. Current : : 750 VDC 15 A Thermal EMF : <1 µV/K : -55°C...155°C 15 A ENVIRONMENTAL Operating Temperature Range MECHANICAL Resistor Material : NiCr-Foil Substrate : Al2O3 Housing : Epoxy + Al-heatsink Connector Material : Cu, tinned, 4-pin Max. torque backplate : 1.0 Nm note1): Specially designed for applications with fast changing electrical load. AlN Willow Technologies Ltd. Shawlands Court, Newchapel Road, Lingfield, Surrey, RH7 6BL, UK Tel. + 44 (0) 1342 835234, Fax. + 44 (0) 1342 834306, e-mail [email protected] web www.willow.co.uk USR UNR 4-4020 TEMPERATURE COEFFICIENT 600 +5 ppm/K dR/R (ppm ) 400-5 ppm/K 200 No minal-Spread +/-2,3 ppm/K 0 +2,2 ppm/K -200 -1,8 ppm/K No minal-dR/R -400 No minal-Spread +/-2,3 ppm/K -600 -50 0 -25 25 50 100 75 125 Tem perature (°C) DERATING CURVE Power ( % from nominal power) 120 100 80 60 40 20 0 25 50 85 100 115 130 145 155 Temperature of the backplate (°C) DIMENSIONS from R ≤ 0R1 leads with d=0.8mm Dimensions in mm HOW TO ORDER USR 4-4020 0R3 D 0.25% TK3 UNR 4-4020 50R D 0.01% TK1 Willow Technologies Ltd. Shawlands Court, Newchapel Road, Lingfield, Surrey, RH7 6BL, UK Tel. + 44 (0) 1342 835234, Fax. + 44 (0) 1342 834306, e-mail [email protected] web www.willow.co.uk