Datasheet

LTO 30
www.vishay.com
Vishay Sfernice
Revision: 16-Nov-17
2
Document Number: 50049
For technical questions, contact: [e-mail]
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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 
R
TH (j - c)
: Thermal resistance value measured between 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, thermal pad), and the quality of
the fastening device.

R
TH (h - a)
: Thermal resistance of the heatsink.
Example: 
R
TH (c - a)
for LTO 30 power rating 10 W at ambient temperature +25 °C
Thermal resistance R
TH (j - c)
: 4.2 °C/W 
Considering equation
(1)
we have:
T = 150 °C - 25 °C = 125 °C 
R
TH (j - c)
+ R
TH (c - h)
+ R
TH (h - a)
= = = 12.5 °C/W
R
TH (c - h)
R
TH (h - a)
= 12.5 °C/W - 4.2 °C/W = 8.3 °C/W
with a thermal grease R
TH (c - h)
= 1 °C/W, we need a heatsink with R
TH (h - a)
= 7.3 °C/W.
PERFORMANCE
TESTS CONDITIONS REQUIREMENTS
Momentary Overload
EN 60115-1
1.5 Pr / 5 s
U
S
< 1.5 U
L
± (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
P
T
R
TH (j - c)
R
TH (c - h)
R
TH (h - a)
++
----------------------- --------------------------- -------------------------- ---------------
1
=
T
P
-------
125
10
--------