Data sheet E 4/1.718 - 09198 RTO 20 45iV 20 W at 25C mounted heatsink power resistor - thick film technology Two versions of this thick film resistors are available : - a radial lead version for PCB mounting, - a flat lead version for surface mounting. The well know TO 220 package is tight and easy to mount. The main features of this product are : A HIGH DENSITY OF POWER DISSIPATION (THE RATIO POWER DISSIPATION VOLUME IS HIGH) A LARGE RANGE OF OHMIC VALUE A NEGLIGEABLE INDUCTANCE AN EASY MOUNTING RTO 20F RTO 20C 4.5 4.5 10.1 O 3.6 10.1 1.3 12.5 15 O 3.6 12.5 8.8 1.3 15 8.8 2 3 13.7 1.8 0,3 5.08 O 0.8 2.5 5.08 Fig. 1 Fig. 2 Dimensions in mm Tolerance unless otherwise specified : 0,4 mm. SPECIFICATIONS MECHANICAL MECHANICAL PROTECTION... RESISTIVE ELEMENT... END CONNECTIONS... WEIGHT... ELECTRICAL insulated case thick film tinned copper 2 g max. RESISTOR RANGE... TOLERANCES standard... DISSIPATION AND ASSOCIATED... THERMAL RESISTANCE... DIMENSIONAL PACKAGE... standard... TO 220 on request... D2 pack DD pack please consult Sfernice ENVIRONMENTAL TEMPERATURE RANGE... -55C +155C CLIMATIC CATEGORY... 55 / 155 / 56 SEALED... sealed container solder immersion TEMPERATURE COEFFICIENT... standard... on request... LIMITING ELEMENT VOLTAGE... DIELECTRIC STRENGTH... INSULATION RESISTANCE... INDUCTANCE... CRITICAL RESISTANCE... 0,046 to 1 M 1% ... 10% onto a heatsink 20 W at +25C Rth (j-c) : 6,5C/W free air : 2 W at +25C see table 1 150 ppm/C 50 ppm/C 250 V 2000 V* RMS 106 M 0,1 H 3,12 k * (between leads and case) PERFORMANCES Table 1 TESTS CONDITIONS TYPICAL DRIFTS 2 Pr / 5 s Us < 1,5 UL (0,25 % 0,05 ) 5 cycles Nominal power Pn - 55C +155C (0,5 % 0,05 ) 1000 hours Pr at + 25C (1 % 0,05 ) 56 days H.R. 95% (0,5 % 0,05 ) 1000 h - 40% Pr at +100C (0,5 % 0,05 ) SHORT TIME OVERLOAD CLIMATIC SEQUENCE LOAD LIFE HUMIDITY (steady state) HIGH TEMPERATURE EXPOSURE POWER RATING CHART PARTICULAR FEATURES The temperature of the heater should maintained in the limit specified. To improve the thermal conductivity, surfaces in contact should be laid on with a silicone grease and the torque applied on the screw for tightening should be around 1 Nn. Fig. 3 Table 2 0,046 Ohmic values Tolerances 0,5 1% at 10% standard Temperature coefficient 0,1 300ppm/C 250ppm/C 150ppm/C for R 0,1 50 ppm/C on request ENERGY CURVE Fig. 4 75 50 10 25 0 0 20 25 40 60 80 100 120 140 AMBIENT TEMPERATURE IN DEGREES CELSIUS 155 ENERGY IN JOULE % RATED POWER 100 1 0,1 OVERLOADS In any case the applied voltage must be lower than the maximum overload voltage of 375 V. Power versus ambient temperature derating factor : From 25C (ambient temperature) for a temperature increase of 1,55 the overload power must be reduced by 1%. The corresponding derating factor is obtained by the formule : ambient -25C R=1- 155C Non repetitive overload 1s The acceptable power is obtained by the formula : E (J) Pa = xR T (s) E : being the energy (fig. 4) T : duration of overload R : power derating factor i.e. : duration of overload 10 ms ambient temperature 45 energy : 2 J (fig. 4). 0,01 10-6 10-5 10-4 10-3 10-2 OVERLOAD DURATION IN SECOND Impulsional train of overload : Taking into account the average power the power acceptable is : Pn Pa = x R K with Pn : nominal power K : ratio between the duration of overload impulse and the period between 2 pulses R : being the power reduction factor. CONDITIONING Tube of 50 units. MARKING Series, style, ohmic value (in ), tolerance (in %), manufacturing date, SFERNICE trademark. 45 -25 = 0,87 155 E 2 Pa = xR = x 0,87 = 174 W T 0,01 R=1- ORDERING PROCEDURE SERIE STYLE CONNECTIONS OHMIC VALUE TOLERANCE SPECIAL DESIGN RTO 20 F 100 k 10% xxx 1% 2% 5% 10 % Optional on request : special TCR shape, etc. 45iV VISHAY S.A. International Department 199, Boulevard de la Madeleine B.P. 1159 F 06003 NICE CEDEX 1 Tel. : (33) 04 93 37 27 27 Fax : (33) 04 93 37 27 26 F : radial leads C : surface mounting