rch www.vishay.com vishay sfernice revision: 23-may-13 1 document number: 50006 for technical questions, contact: sfer@vishay.com this document is subject to change without notice. the products described herein and this document are subject to specific disclaimers, set forth at www.vishay.com/doc?91000 power resistor, for mounting onto a heatsink thick film technology manufactured in cermet thick film technology, these power resistors exhibit remarkable ch aracteristics and the series includes 4 types ranging from 5 w to 50 w. ? designed to be mounted onto a heatsink, the resistors can bear high short time overload s and 3 types of terminations are available. ? the resistors are non inductive and are particularly suitable for high frequency operation and cut-out circuits. features ? 5 w to 50 w ? high power rating ? high overload capabilities up to 2500 v rms ? wide resistance range from 0.24 m ? to 1 m ? ? high thermal capacity up to 0.8 c/w ? easy mounting ? reduced size and weight ? high insulation: 10 6 m ? ? material categorization: for definitions of compliance please see www.vishay.com/doc?99912 ? ? note ? tolerances unless stated: 0.3 mm dimensions in millimeters model rch5 rch10 rch25 rch50 l 16.6 19 28 47.8 w 9 11 14 15.5 h 16.4 20.6 27.5 29.5 p leads pitch 10.2 12.7 18.3 30.5 f connection pitch 11.3 14.3 18.3 39.7 t 12.5 15.9 19.8 21.4 s 5.357.78 ? d 2.4 2.4 3.2 3.2 weight (g) 45712 ? 2 6 rch...r m2 6 rch...v w h f s l ? d p 6 4.8 6 3 ? 2.1 t 9 rch...s
rch www.vishay.com vishay sfernice revision: 23-may-13 2 document number: 50006 for technical questions, contact: sfer@vishay.com this document is subject to change without notice. the products described herein and this document are subject to specific disclaimers, set forth at www.vishay.com/doc?91000 ? standard electrical specifications model resistance range ? rated power p 25 c w tolerance % temperature coefficient ppm/c rch 0.24 to 1 m e24 range 5 to 50 1, 2, 5, 10 150, 250 mechanical specifications mechanical protection insulated case resistive element cermet substrate alumina connections tinned copper alloy environmental specifications temperature range - 55 c to + 125 c climatic category 55/125/56 flammability iec 60695-11-5 2 applications 30 s separated by 60 s technical specifications dissipation and associated onto a heatsink power rating: ? chassis mounted ? unmounted 5 w to 50 w 2 w to 5.5 w temperature coefficient 150 ppm/c insulation resistance 10 6 m ? total inductance ? 0.1 h performance tests conditions requirements momentary overload nf en140000 cei 115_1 2 pr/5 s u s < 1.5 u l < (0.25 % + 0.05 ? ) rapid temperature change nf en140000 125 c cei 68215 test na 5 cycles - 55 c to + 125 c < (0.25 % + 0.05 ? ) load life nf en140000 cei 115_1 1000 h pr at + 25 c < (0.5 % + 0.05 ? ) humidity (steady state) 56 days rh 95 % mil-std-202 method 103 b and c < (0.5 % + 0.05 ? ) resistance value in relation to tolerance and tcr resistance values < 1 ? > 1 ? standard tolerances 5 % 10 % standard tcr 250 ppm/c 150 ppm/c tolerance on request 1 % to 2 % special features model rch 5 rch 10 rch 25 rch 50 power rating-cha ssis mounted 5 w 10 w 25 w 50 w power rating-unmounted 2 w 2.5 w 4 w 5.5 w thermal resistance r th (j - c) 4.8 c/w 3.2 c/w 1.4 c/w 0.8 c/w limiting element voltage (v rms ) 160 v 250 v 550 v 1285 v max. overload voltage (v rms ) 320 v 500 v 1100 v 2500 v dielectric strength (v rms ) 50 hz, 1 min mil-std-202 method 301 10 ma max. 2000 v 2000 v 3500 v 3500 v critical resistance 5120 ? 6250 ? 12 100 ? 33 024 ?
rch www.vishay.com vishay sfernice revision: 23-may-13 3 document number: 50006 for technical questions, contact: sfer@vishay.com this document is subject to change without notice. the products described herein and this document are subject to specific disclaimers, set forth at www.vishay.com/doc?91000 recommendations for mounting onto a heatsink ? surfaces in contact must be carefully cleaned. ? the heatsink must have an acceptable flatness: from 0.05 mm to 0.1 mm/100 mm. ? roughness of the heatsink must be around 6.3 m. in order to improve the rmal conductivity, surface s in contact (alumina, heatsink) are coated with a silicone grease (type sl 340 from rh?ne-poulenc or dow 340 from dow corning). ? the fastening of the resistor to the heatsink is under pressure control of tw o screws (not supplied). ? in order to improve the dissipation, either for ced-air cooling or liquid cooling may be used. ? a low thermal radiation of the ca se allows several resistors to be mounted onto the same heatsink. ? do not forget to respect an insula tion value between two resistors (die lectric strength in dry air 1 kv/mm). ? in any case the hot spot temperature, measured locally on the case must not exceed 125 c. ? tests should be performed by the user. choice of the heatsink the user must choose according to the working condit ions of the component (pow er, room temperature). ? maximum working temperature must not exceed 125 c. the dissipated power is simply calculated by the following ratio: p: expressed in w ? t: difference between maxi mum working temperature and room temp erature or fluid c ooling temperature. r th (j - c) : thermal resistance value measured betw een resistive layer and outer side of the resistor. it is the thermal resistance of the component. r th (c - h) : thermal resistance value measured between outer side of the resistor and upper side of the heatsink. this is the thermal resistance of the interface (grease, the rmal pad), and the quality of the fastening device. r th (h - a) : thermal resistance of the heatsink. ? example: ? r th (c - a) for rch 25 power rating 20 w at ambient tempera ture + 50 c ? thermal resistance r th (j - c) : 2.5 c/w ? considering equation (1) we have: ? t = ? 125 c - 50 c ? 75 c ? r th (j - c) = 1.4 c/w (special features) ? r th (j - c) + r th (c - h) + r th (h - a) = = = 3.75 c/w ? r th (c - h) + r th (h - a) ? 3.75 c/w - 1.4 c/w ? 2.35 c/w ? with a thermal grease r th (c - h) = 1 c/w, we need a heatsink with r th (h - a) = 1.35 c/w tightening torque on heatsink rch 5 rch 10 rch 25 rch 50 0.5 nm 0.6 nm 0.7 nm 1 nm p ? t r th (j - c) r th (c - h) r th (h - a) ++ ------------------------------------------------------------------------------------------- 1 ?? = ? t p ------- 75 20 ---- -
rch www.vishay.com vishay sfernice revision: 23-may-13 4 document number: 50006 for technical questions, contact: sfer@vishay.com this document is subject to change without notice. the products described herein and this document are subject to specific disclaimers, set forth at www.vishay.com/doc?91000 overloads the applied voltage must always be lower than the maximum overload voltage as shown in the special features table. ? the values indicated on the graph below are applicable to resistors in air or mounted onto a heatsink. energy curve power curve power rating for resistors mounted onto heat sink and thermal resistance of 1 c/w. ? to improve the thermal conductivity, surfaces in contact should be coated with a silicone grease. marking model, style, resistance value (in ? ), tolerance (in %), manufacturing date, vishay sfernice trademark. 0.01 0.1 1 10 100 ener g y in joule s overload duration in s rch50 rch25 rch10 rch5 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 10 100 1000 10 000 100 000 1 000 000 power in w overload duration in s rch50 rch25 rch10 rch5 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 0 25 50 75 100 rated power in % 0 ambient temperature in c 20 40 60 80 100 120 140 rch 5 rch 10 rch 25 rch 50
rch www.vishay.com vishay sfernice revision: 23-may-13 5 document number: 50006 for technical questions, contact: sfer@vishay.com this document is subject to change without notice. the products described herein and this document are subject to specific disclaimers, set forth at www.vishay.com/doc?91000 ordering information rch 25 3.3 k ? 5 % r xxx model style resistance value tolerance optional 1 % 2 % 5 % 10 % connections optional s: flat with hole r: round lead v: m2 screw custom design optional global part number information global model size leads ohmic value tolerance packaging special rch 05 10 25 50 r = round lead v = m2 screw s = flat with hole the first four digits are significant figures and the last digit specifies the number of zeros to follow. r designates decimal point. 4r700 = 4.7 ? 48701 = 48 700 ? r0100 = 0.01 ? r6800 = 0.68 ? 27000 = 2700 ? = 2.7 k ? f = 1 % g = 2 % j = 5 % k = 10 % s06 = bag 25 pieces as applicable ex = xxx 10s3300j03 c h r 0s6
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