LTO 50
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Revision: 16-Nov-17 1Document Number: 50050
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
Power Resistor Thick Film Technology
DESIGN SUPPORT TOOLS
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
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.
Note
Tolerances unless stated: ± 0.3 mm
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Available
Models
DIMENSIONS in millimeters
STANDARD ELECTRICAL SPECIFICATIONS
MODEL SIZE
RESISTANCE
RANGE
RATED POWER
P25 °C
W
LIMITING ELEMENT
VOLTAGE UL
V
TOLERANCE
± %
TEMPERATURE
COEFFICIENT
± ppm/°C
CRITICAL
RESISTANCE
LTO 50 TO-220 0.010 to 550K 50 500 1, 2, 5, 10 150, 250, 700, 900 5K
3.2
16.2
10.4
1.8
5.08
0.6
3.5
1.3
0.8
12.7
Ø 3.2
3.2
MECHANICAL SPECIFICATIONS
Mechanical Protection Molded
Resistive Element Thick film
Substrate Alumina
Connections Tinned copper
Weight 2 g max.
Mounting Torque 1 Nm
ENVIRONMENTAL SPECIFICATIONS
Temperature Range -55 °C to +150 °C
Climatic Category 55 / 155 / 56
Flammability IEC 60695-11-5
2 applications 30 s
separated by 60 s
TECHNICAL SPECIFICATIONS
Dissipation and Associated Onto a heatsink
Power Rating and
Thermal Resistance
of the Component
50 W at +25 °C (case temp.)
RTH (j - c): 2.5 °C/W
Free air:
2.5 W at +25 °C
Temperature Coefficient See Performance table
Standard ± 150 ppm/°C
Dielectric Strength
MIL STD 202
1500 VRMS - 1 min
10 mA max.
Insulation Resistance 104 M
Inductance 0.1 μH
LTO 50
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Revision: 16-Nov-17 2Document Number: 50050
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
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:
P: Expressed in W
T: Difference between maximum working temperature and room
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 LTO 50 power rating 10 W at ambient temperature +25 °C
Thermal resistance RTH (j - c): 2.5 °C/W
Considering equation (1) we have:
T = 150 °C - 25 °C = 125 °C
RTH (j - c) + RTH (c - h) + RTH (h - a) = = = 12.5 °C/W
RTH (c - h) + RTH (h - a) = 12.5 °C/W - 2.5 °C/W = 10 °C/W
with a thermal grease RTH (c - h) = 1 °C/W, we need a heatsink with RTH (h - a) = 9 °C/W.
PERFORMANCE
TESTS CONDITIONS REQUIREMENTS
Momentary Overload
EN 60115-1
1.5 Pr / 5 s
US < 1.5 UL
± (0.5 % + 0.005 )
Rapid Temperature Change
EN 60115-1
IEC 60068-2-14 Test Na
5 cycles
-55 °C to +155 °C
± (0.5 % + 0.005 )
Load Life EN 60115-1
1000 h Pr at +25 °C ± (1 % + 0.005 )
Humidity (Steady State) MIL-STD-202
method 103 B cond. D ± (0.5 % + 0.005 )
Vibration MIL-STD-202
method 204 cond. D ± (0.2 % + 0.005 )
Terminal Strength MIL-STD-202
method 211 cond. A1 ± (0.2 % + 0.005 )
Shock 100G, MIL-STD-202
method 213 cond. I ± (0.5 % + 0.005 )
SPECIAL FEATURES
Resistance Values 0.010 0.015 0.1 0.5
Tolerances ± 1 % at ± 10 %
Typical Temperature Coefficient
(-55 ° to +155 °C) ± 900 ppm/°C ± 700 ppm/°C ± 250 ppm/°C ± 150 ppm/°C
PT
RTH (j - c) RTH (c - h) RTH (h - a)
++
----------------------- --------------------------- -------------------------- ---------------
1
=
T
P
------
125
10
--------
LTO 50
www.vishay.com Vishay Sfernice
Revision: 16-Nov-17 3Document Number: 50050
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
OVERLOADS
In any case the applied voltage must be lower than the
maximum overload voltage of 750 V.
The values indicated on the graph below are applicable to
resistors in air or mounted onto a heatsink.
ENERGY CURVE
POWER CURVE
POWER RATING
The temperature of the case should be maintained within the
limits specified.
To improve the thermal conductivity, surfaces in contact
should be coated with a silicone grease and the torque
applied on the screw for tightening should be around 1 Nm.
MARKING
Model, style, resistance value (in ), tolerance (in %),
manufacturing date, Vishay Sfernice trademark.
0.01
0.1
1
10
100
ENERGY IN JOULES
OVERLOAD DURATION IN s
10-7 10-6 10-5 10-4 10-3 10-2 10-1 100
100
1000
10 000
100 000
1 000 000
POWER IN W
OVERLOAD DURATION IN s
10-7 10-6 10-5 10-4 10-3 10-2 10-1 100
PACKAGING
Tube of 50 units
0 20 40 60 80 100 120 140 150
100
125
75
50
25
0
RATED POWER IN %
CASE TEMPERATURE IN °C
LTO 50
www.vishay.com Vishay Sfernice
Revision: 16-Nov-17 4Document Number: 50050
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
ORDERING INFORMATION
LTO 50 F 2.7 k± 1 % xxx TU50 e3
MODEL STYLE CONNECTIONS RESISTANCE VALUE TOLERANCE
± 1 %
± 2 %
± 5 %
± 10 %
CUSTOM DESIGN
optional
on request:
special TCR,
shape etc.
PACKAGING LEAD (Pb)-FREE
GLOBAL PART NUMBER INFORMATION
GLOBAL
MODEL SIZE LEADS OHMIC VALUE TOLERANCE PACKAGING LEAD (Pb)-FREE
LTO 050 F = radial leads The first four digits are
significant figures and the
last digit specifies the
number of zeros to follow.
R designates decimal point.
48R70 = 48.7
48701 = 48 700
10002 = 100 000
R0100 = 0.01
R4700 = 0.47
27000 = 2700 = 2.7 k
F = 1 %
G = 2 %
J = 5 %
K = 10 %
T = tube
tube 50 pieces
E3 = pure tin
RELATED DOCUMENTS
APPLICATION NOTES
Potentiometers and Trimmers www.vishay.com/doc?51001
Guidelines for Vishay Sfernice Resistive and Inductive Components www.vishay.com/doc?52029
050F270 0 T 3T OL 0JE
Legal Disclaimer Notice
www.vishay.com Vishay
Revision: 08-Feb-17 1Document Number: 91000
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