333 3 LTO 50 www.vishay.com Vishay Sfernice Power Resistor Thick Film Technology FEATURES 50 W at 25 C case temperature heatsink mounted Direct mounting ceramic on heatsink Broad resistance range: 0.010 to 550 k Non inductive TO-220 package: compact and easy to mount Material categorization: for definitions of compliance please see www.vishay.com/doc 99912 LINKS TO ADDITIONAL RESOURCES 3D Models LTO series are the extension of RTO types. We used the direct ceramic mounting design (no metal tab) of our RCH power resistors applied to semiconductor packages. DIMENSIONS in millimeters 3.2 10.4 3.2 16.2 3.2 1.3 3.5 12.7 0.8 0.6 1.8 5.08 Note Tolerances unless stated: 0.3 mm STANDARD ELECTRICAL SPECIFICATIONS RESISTANCE RATED POWER LIMITING ELEMENT TEMPERATURE CRITICAL TOLERANCE MODEL SIZE RANGE P VOLTAGE U COEFFICIENT RESISTANCE 25 C L % W V ppm/C 0.01 to < 0.5 50 500 5, 10 250, 700, 900 n/a LTO 50 TO-220 0.5 to 550K 50 500 1, 2, 5, 10 150 5K MECHANICAL SPECIFICATIONS ENVIRONMENTAL SPECIFICATIONS Mechanical Protection Molded Temperature Range -55 C to +150 C Resistive Element Thick film Climatic Category 55 / 155 / 56 Substrate Alumina IEC 60695-11-5 Flammability Application time: t = 10 s a Connections Tinned copper Burning duration: t < 30 s b Weight 2 g max. Mounting Torque 1 Nm Revision: 08-Dec-2021 Document Number: 50050 1 For technical questions, contact: sferfixedresistors 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 DDD D LTO 50 www.vishay.com Vishay Sfernice TECHNICAL SPECIFICATIONS Dissipation and Associated Onto a heatsink 50 W at +25 C (case temp.) R : 2.5 C/W TH (j - c) Power Rating and Thermal Resistance of the Component Free air: 2.5 W at +25 C Temperature Coefficient See Performance table Standard 150 ppm/C Dielectric Strength 1500 V - 1 min RMS MIL STD 202 10 mA max. 4 Insulation Resistance 10 M Inductance 0.1 H PERFORMANCE TESTS CONDITIONS REQUIREMENTS EN 60115-1 Momentary Overload 1.5 Pr / 5 s (0.5 % + 0.005 ) U < 1.5 U S L EN 60115-1 IEC 60068-2-14 Test Na Rapid Temperature Change (0.5 % + 0.005 ) 5 cycles -55 C to +155 C EN 60115-1 Load Life (1 % + 0.005 ) 1000 h Pr at +25 C MIL-STD-202 Humidity (Steady State) (0.5 % + 0.005 ) method 103 B cond. D MIL-STD-202 Vibration (0.2 % + 0.005 ) method 204 cond. D MIL-STD-202 Terminal Strength (0.2 % + 0.005 ) method 211 cond. A1 100G, MIL-STD-202 Shock (0.5 % + 0.005 ) method 213 cond. I SPECIAL FEATURES Resistance Values 0.01 0.015 0.1 0.5 Tolerances 5 %, 10 % 1 %, 2 %, 5 %, 10 % Typical Temperature Coefficient 900 ppm/C 700 ppm/C 250 ppm/C 150 ppm/C (-55 C to +155 C) 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 150 C. The dissipated power is simply calculated by the following ratio: ()1 T P = ------------------------------------------------------------------------------------------- R ++R R TH (j - c) TH (c - h) TH (h - a) P: expressed in W T: difference between maximum working temperature and room temperature R : thermal resistance value measured between resistive layer and outer side of the resistor. It is the thermal resistance of TH (j - c) the component. R : thermal resistance value measured between outer side of the resistor and upper side of the heatsink. This is the TH (c - h) thermal resistance of the interface (grease, thermal pad), and the quality of the fastening device. R : thermal resistance of the heatsink. TH (h - a) Example: R for LTO 50 power rating 10 W at ambient temperature +25 C TH (c - a) Thermal resistance R : 2.5 C/W TH (j - c) (1) Considering equation we have: T = 150 C - 25 C = 125 C T 125 R + R + R = ------ = -------- = 12.5 C/W TH (j - c) TH (c - h) TH (h - a) P 10 R + R = 12.5 C/W - 2.5 C/W = 10 C/W TH (c - h) TH (h - a) with a thermal grease R = 1 C/W, we need a heatsink with R = 9 C/W. TH (c - h) TH (h - a) Revision: 08-Dec-2021 Document Number: 50050 2 For technical questions, contact: sferfixedresistors 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