www.vishay.com 27 RTOP vishay sfernice document number: 50045 revision 20-mar-02 for technical questions, contact sfer@vishay.com mechanical specifications mechanical protection insulated case substrate alumina on insulated base (excluding qRTOP series) resistive element cermet end connections v connections: screw m4 x 6 f connections: faston type tightening torque connections 1 nm tightening torque heatsink 2 nm environmental specifications temperature range - 55c to + 125c climatic category 55 /125/56 power resistors for mounting onto a heatsink thick film technology features up to 4 different ohmic values in the same case 1% tolerance available high power rating wide ohmic value range non inductive easy mounting low thermal radiation of the case standard isotop case (sot 227 b) this series of thick lm power resistors include modules which can incorporate up to 4 different resistor values in the same sot 227b package. two types of terminations are available along with a 4 terminal device for measurement applications in the case of the single resistor version. this product range bene ts from vishay sfernice s experience in thick lm power resistor technology i.e high power: volume ratio, low tolerance or individual resistors and excellent overload capabilities (due to the trimming technique). v connections f connections (?faston? type) 4 10 12.5 15 30 38 12.5 25 ? 4.2 ? 1.8 6.3 4 10 19.3 23 25 15 30 38 RTOP tolerances unless otherwise speci ed: ?0.3mm dimensions in millimeters resistance range 0.046 to 1m ? standard tolerance 1% to 10% power rating 20w to 200w at + 25 c temperature coef cient standard 300 ppm/ ? c (r < 1) 150 ppm/ ? c (r > 1) insulation resistance > 10 6 m ? electrical specifications
document number: 50045 revision 20-mar-02 www.vishay.com 28 RTOP vishay sfernice for technical questions, contact sfer@vishay.com model RTOP 200 RTOP 100 dRTOP 100 dRTOP 50 tRTOP 40 tRTOP 30 qRTOP 35 qrto p 20 power rating at + 25 c chassis mounted resistors 200w 100w 100w 50w 40w 30w 35w 20w unmounted resistors 5w 5w 3.5w 3.5w 2w 2w 1.5w 1.5w thermal resistance (per resistor) 0.5 c/w 1 c/w 0.5 c/w 1 c/w 0.83 c/w 1.11 c/w 0.71 c/w 1.25 c/w limiting voltage 1500v 1500v 500v 500v 300v 300v 300 v 300v dielectric strength 2500v 2500v 2500v 2500v 2500v 2500v base = c ommon connections/chassis dielectric strength - - 4000v 4000v 4000v 4000v 40 00v 4000v connections/resistors ohmic value range 0.046 to 1m ? 0.092 to 1m ? 0.046 to 1m ? 0.046 to 1m ? tolerance 1% to 10% 1% to 10% 1% to 10% 1% to 10% electrical diagrams r r r2 r1 r2 r1 r3 r2 r1 r3 r4 performance tests conditions typical drifts momentary overload 2.5pn/5 seconds < ( 0.25% 0.05 ? ) rapid temperature change 5 cycles - 55 c +125 c < (0.25% 0.05 ? ) load life pn at 25 c 1000 hours < (0.5% 0.05 ? ) humidity (steady state) 56 days 95% r.h. < (0.5% 0.05 ? ) special features power resistors for mounting onto a heatsink thick film technology shunt version grounded base
www.vishay.com 29 RTOP vishay sfernice document number: 50045 revision 20-mar-02 for technical questions, contact sfer@vishay.com choice of heatsink the user must choose the heatsink according to the working conditions of the component (power, room temperature). maximum working temperature must not exceed 125 c. the dissipated power is simply calculated by the following ratio: p = p: expressed in w ? t: difference between maximum working temperature and room temperature. r th: (j-c): thermal resistance value measured between resistive layer and outer side of the resistor. it is the thermal resistance of the component (see table special features). r th: (c-a): thermal resistance value measured between outer side of the resistor and room temperature. it is the thermal resistance of the heatsink depending on the heatsink itself (type, shape) and the quality of the fasten ing device. example: r th: (c-a) for RTOP 200 power rating 130w at ambient temperature + 30 c. thermal resistance (see table 1) r th (j-c): 0.5 c/w ? t 125 c - 30 c - 95 c rth ( j-c) + rth ( c-a) = = = 0.73 c/w rth ( j-c) 0.5 c/w rth (c-a) 0.73 c/w - 0.5 c/w 0.23 c/w ? t [r th (j-c) + r th (c-a)] (1) recommendations for mounting onto a heatsink surfaces in contact must be carefully cleaned. the heatsink must have an acceptable atness: from 0.05mm to 0.1mm/100mm. roughness of the heater must be around 6.3m. in order to improve thermal conductivity, surfaces in contact (alumina, heatsink) are laid on with a silicone grease (type si 3 40 from rh ? ne-poulenc or dow 340 from dow corning). tightening torque on heater: 2 nm for the electrical connections, it is recommended to use m4 x 6 screws and if necessary a washer of 1mm thickness. the recommended screw tightening torque is 1 nm. 130 ? t p 95 power resistors for mounting onto a heatsink thick film technology
document number: 50045 revision 20-mar-02 www.vishay.com 30 RTOP vishay sfernice for technical questions, contact sfer@vishay.com overloads the applied power is 2.5 x rated power for 5 s with a max voltage of 2 x nominal voltage. accidental overload: the values indicated in the graph below are applicable to resistors in air or mounted onto a heatsink. in case of multi-resistor devices, (dRTOP, tRTOP and qRTOP) the results apply to each resistor value in the device. power rating chart the temperature of the heater should be maintained in the limit speci ed. to improve the thermal conductivity, surfaces in contact should be laid on with a silicon grease and the torque applied on the screw for tightening should be around 2 nm. marking series, style, ohmic value (in ), tolerance (in %), manufacturing date, vishay trade mark. % rated power 0 20 40 60 80 100 120 140 heatsink temperature in degrees celsius energy curve ordering information RTOP 200 3.2 1% % v r1 t1 r2 t2 model style ohmic value c onnections custom design RTOP 100 optional to be precise v: screw optional dRTOP 50 1% for each f: faston type tRTOP 40 2% resistor vs} RTOP qRTOP 30 5 % fs} shunt 35 10 % 20 absolute tolerance per resistor power resistors for mounting onto a heatsink thick film technology overload duration in seconds energy in joules 1.10 -7 1.10 -6 1.10 -5 1.10 -4 1.10 -3 1.10 -2 1.10 -1 1 RTOP dRTOP tRTOP and qRTOP 0.01 0.1 1 10 100 1000 0 20 40 60 80 100
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