RCH www.vishay.com Vishay Sfernice Power Resistor, for Mounting onto a Heatsink Thick Film Technology FEATURES • 5 W to 50 W • High power rating • High overload capabilities up to 2500 VRMS • Wide resistance range from 0.24 to 1 M • High thermal capacity up to 0.8 °C/W • Easy mounting • Reduced size and weight Manufactured in cermet thick film technology, these power resistors exhibit remarkable characteristics 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 overloads and 3 types of terminations are available. The resistors are non inductive and are particularly suitable for high frequency operation and cut-out circuits. • High insulation: 106 M • Material categorization: for definitions of compliance please see www.vishay.com/doc?99912 DIMENSIONS in millimeters RCH...R RCH...V M2 Ø2 RCH...S 6 H 6 W 6 Ø 2.1 3 4.8 S L P F 6 ØD T MODEL RCH5 RCH10 9 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 5.3 5 7.7 8 ØD 2.4 2.4 3.2 3.2 4 5 7 12 Weight (g) Note • Tolerances unless stated: ± 0.3 mm Revision: 06-Jul-15 Document Number: 50006 1 For technical questions, contact: [email protected] 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 RCH www.vishay.com Vishay Sfernice STANDARD ELECTRICAL SPECIFICATIONS MODEL RESISTANCE RANGE RATED POWER P25 °C W TOLERANCE ±% TEMPERATURE COEFFICIENT ± ppm/°C SERIES RCH 5 0.24 to 1M 5 1, 2, 5, 10 150, 250 E24 range RCH 10 0.24 to 1M 10 1, 2, 5, 10 150, 250 E24 range RCH 25 0.24 to 1M 25 1, 2, 5, 10 150, 250 E24 range RCH 50 0.24 to 1M 50 1, 2, 5, 10 150, 250 E24 range MECHANICAL SPECIFICATIONS TECHNICAL SPECIFICATIONS Mechanical Protection Dissipation and Associated Insulated case Resistive Element Cermet Substrate Alumina Connections Tinned copper alloy ENVIRONMENTAL SPECIFICATIONS Temperature Range -55 °C to +125 °C Climatic Category Flammability 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 106 M Total Inductance 0.1 μH 55 / 125 / 56 IEC 60695-11-5 2 applications 30 s separated by 60 s PERFORMANCE TESTS Momentary Overload Rapid Temperature Change Load Life Humidity (Steady State) CONDITIONS REQUIREMENTS NF EN140000 CEI 115_1 2 Pr/5 s US < 1.5 UL < ± (0.25 % + 0.05 ) NF EN140000 125 °C CEI 68215 Test Na 5 cycles -55 °C to +125 °C < ± (0.25 % + 0.05 ) NF EN140000 CEI 115_1 1000 h Pr at +25 °C < ± (0.5 % + 0.05 ) 56 days RH 95 % MIL-STD-202 Method 103 B and C < ± (0.5 % + 0.05 ) RESISTANCE VALUE IN RELATION TO TOLERANCE AND TCR <1 Resistance Values >1 ±5% ± 10 % Standard Tolerances Standard TCR ± 250 ppm/°C ± 150 ppm/°C Tolerance on Request ± 1 % to ± 2 % SPECIAL FEATURES MODEL RCH 5 RCH 10 RCH 25 Power Rating-Chassis Mounted 5W 10 W 25 W 50 W Power Rating-Unmounted 2W 2.5 W 4W 5.5 W 0.8 °C/W Thermal Resistance Rth (j - c) RCH 50 4.8 °C/W 3.2 °C/W 1.4 °C/W Limiting Element Voltage (VRMS) 160 V 250 V 550 V 1285 V Max. Overload Voltage (VRMS) 320 V 500 V 1100 V 2500 V Dielectric Strength (VRMS) 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 Revision: 06-Jul-15 Document Number: 50006 2 For technical questions, contact: [email protected] 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 RCH www.vishay.com Vishay Sfernice 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 μm. In order to improve thermal conductivity, surfaces in contact (alumina, heatsink) are coated with a silicone grease (type Sl 340 from Rhône-Poulenc or Dow 340 from Dow Corning). • The fastening of the resistor to the heatsink is under pressure control of two screws (not supplied). Tightening Torque on heatsink RCH 5 RCH 10 RCH 25 RCH 50 0.5 Nm 0.6 Nm 0.7 Nm 1 Nm • In order to improve the dissipation, either forced-air cooling or liquid cooling may be used. • A low thermal radiation of the case allows several resistors to be mounted onto the same heatsink. • Do not forget to respect an insulation value between two resistors (dielectric 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 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: 1 T P = ------------------------------------------------------------------------------------------R TH (j - c) + R TH (c - h) + R TH (h - a) P: Expressed in W T: Difference between maximum working temperature and room temperature or fluid cooling temperature. Rth (j - c): Thermal resistance value measured between resistive layer and outer side of the resistor. It is the thermal resistance of the component. Rth (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, thermal pad), and the quality of the fastening device. Rth (h - a): Thermal resistance of the heatsink. Example: RTH (c - a) for RCH 25 power rating 20 W at ambient temperature +50 °C Thermal resistance RTH (j - c): 2.5 °C/W Considering equation (1) we have: T = 125 °C - 50 °C 75 °C RTH (j - c) = 1.4 °C/W (Special Features) T RTH (j - c) + RTH (c - h) + RTH (h - a) = ------- = 75 ----- = 3.75 °C/W P 20 RTH (c - h) + RTH (h - a) 3.75 °C/W - 1.4 °C/W 2.35 °C/W with a thermal grease RTH (c - h) = 1 °C/W, we need a heatsink with RTH (h - a) = 1.35 °C/W Revision: 06-Jul-15 Document Number: 50006 3 For technical questions, contact: [email protected] 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 RCH www.vishay.com Vishay Sfernice OVERLOADS POWER RATING 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. For resistors mounted onto heatsink and thermal resistance of 1 °C/W. To improve the thermal conductivity, surfaces in contact should be coated with a silicone grease. 100 ENERGY CURVE RATED POWER IN % RCH 5 RCH 10 ENERGY IN JOULES 100 RCH50 RCH25 10 1 RCH10 RCH5 0.1 75 RCH 25 RCH 50 50 25 0 0 0.01 10-7 20 40 60 80 100 120 140 AMBIENT TEMPERATURE IN °C -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 10 0 OVERLOAD DURATION IN s MARKING Model, style, resistance value (in ), tolerance (in %), manufacturing date, Vishay Sfernice trademark. POWER CURVE 1 000 000 POWER IN W 100 000 RCH50 RCH25 10 000 1000 RCH10 RCH5 100 10 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 OVERLOAD DURATION IN s Revision: 06-Jul-15 Document Number: 50006 4 For technical questions, contact: [email protected] 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 RCH www.vishay.com Vishay Sfernice ORDERING INFORMATION RCH 25 3.3 k ±5% R xxx MODEL STYLE RESISTANCE VALUE TOLERANCE CONNECTIONS CUSTOM DESIGN Optional ±1% ±2% ±5% ± 10 % Optional S: Flat with hole R: Round lead V: M2 screw Optional GLOBAL PART NUMBER INFORMATION R GLOBAL MODEL RCH Revision: 06-Jul-15 C H 1 0 S 3 3 0 0 0 J S 0 6 3 SIZE LEADS OHMIC VALUE TOLERANCE PACKAGING SPECIAL 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 Document Number: 50006 5 For technical questions, contact: [email protected] THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. 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