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
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DESIGN SUPPORT TOOLS
Models
Available
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
LTO 50 TO-220 0.010 to 550K 50 500 1, 2, 5, 10 150, 250, 700, 900 5K
MECHANICAL SPECIFICATIONS TECHNICAL SPECIFICATIONS
Mechanical Protection Molded
Dissipation and Associated Onto a heatsink
Resistive Element Thick film
50 W at +25 C (case temp.)
Power Rating and
Substrate Alumina
R : 2.5 C/W
TH (j - c)
Thermal Resistance
Connections Tinned copper Free air:
of the Component
2.5 W at +25 C
Weight 2 g max.
Mounting Torque 1 Nm Temperature Coefficient See Performance table
Standard 150 ppm/C
ENVIRONMENTAL SPECIFICATIONS
Dielectric Strength 1500 V - 1 min
RMS
Temperature Range -55 C to +150 C
MIL STD 202 10 mA max.
Climatic Category 55 / 155 / 56
4
Insulation Resistance 10 M
IEC 60695-11-5
Flammability 2 applications 30 s Inductance 0.1 H
separated by 60 s
Revision: 16-Nov-17 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
LTO 50
www.vishay.com
Vishay Sfernice
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 0.010 0.015 0.1 0.5
Tolerances 1 % at 10 %
Typical Temperature Coefficient
900 ppm/C 700 ppm/C 250 ppm/C 150 ppm/C
(-55 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 R : Thermal resistance value measured between outer side of
TH (c - h)
T: Difference between maximum working temperature and room the resistor and upper side of the heatsink. This is the thermal
temperature resistance of the interface (grease, thermal pad), and the quality of
R : Thermal resistance value measured between resistive layer the fastening device.
TH (j - c)
and outer side of the resistor. It is the thermal resistance of the R : Thermal resistance of the heatsink.
TH (h - a)
component.
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: 16-Nov-17 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