USR UNR 4-T220 4-T220B 4-T221 USS UNS 4-T220 • Highest Stability • Near Temperature Independent • Lowest Tolerances • Low Capacitance and Inductance • High Power • Available also 2-pin version SPECIFICATIONS ELEKTRICAL USR 4-T220 UNR 4-T220 note1) 0R2...80R Resistance range : 0R2...80R Nominal power : 1.5 W (70°C) without heatsink 10 W* 15 W* * with heatsink 10.8 K/W 6.8 K/W Thermal Resistance Rthj-c : Tolerances : from 0R5 : from 10R : from 50R : Stability : Temperature coefficient : Voltage Proof Thermal EMF : : 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% 0.01% max. ±5 ppm/K (-55...155)°C typ. ±3 ppm/K (-55...125)°C upon request ±1 ppm/K (0...60)°C 1 kVDC < 1 µV/K ENVIRONMENTAL Operating Temperature Range : -55°C...155°C MECHANICAL Resistor Material : NiCr-Foil AlN Substrate : Al2O3 Housing : Epoxy + heatsink Cu nickel plated Connector Material : Cu, tinned, 4-pin Max. torque backplate : 1.0 Nm note1): Specially designed for applications with fast changing electrical load. TEMPERATURE COEFFICIENT dR/R (ppm ) 600 +5 ppm/K 400 -5 ppm/K 200 0 +2,2 -200 ppm/K No minal-Spread -1,8 ppm/K +/-2,3 ppm/K No minal-dR/R -400 No minal-Spread +/-2,3 ppm/K -600 -50 -25 0 25 50 Tem perature (°C) 75 100 125 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 USS UNS 4-T220 4-T220B 4-T221 4-T220 DERATING CURVE Power ( % from nominal power) 120 100 80 60 40 20 0 25 50 DIMENSIONS 85 100 115 130 145 155 Temperature of the backplate (°C) USR 4-T220 UNR 4-T220 Housing for special demands and small quantities USR 4-T220B / UNR 4-T220B USR 4-T221 / UNR 4-T221 USS 4-T220 / UNS 4-T220 Dimensions in mm HOW TO ORDER USR 4-T220 0R5 D 0.25% TK5 UNR 4-T220B 50R D 0.1% 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