LPS 1100
www.vishay.com
Vishay Sfernice
Revision: 23-Oct-12
2
Document Number: 50059
For technical questions, contact: sfer@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
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 (ceramic,
heatsink) should be coated with a silicone grease (type SI 340 from Blue Star Silicones). Thermal film (type Q-pad II from
Berquist) is also possible, easier and faster to install than grease but with a lower efficiency for the power dissipation.
• The fastening of the resistor to the heatsink is under pressure control of two screws tightened at 2 Nm for full power
availability.
• The following accessories are supplied with each product:
- 2 screws CHC M4 x 25 class 8.8 and 2 M4 contact lock washers for heatsink mounting
- 2 screws TH M4 x 6/6 and 2 M4 contact lock washers for connections. 2 off CHC M4 x 16/16 class 8
CHOICE OF THE HEATSINK AND THE THERMAL INTERFACE
The user must choose the heatsink according to the working conditions of the component (power, room temperature).
Maximum working temperature must not exceed 200 °C. The dissipated power is simply calculated by the following ratio:
P: Expressed in W
T: Difference between maximum working temperature and room temperature or fluid cooling 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: 0.039 °C/W.
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 - h)
+ R
th (h - a)
for LPS 1100 power dissipation 850 W at + 18 °C fluid temperature.
PERFORMANCE
TESTS CONDITIONS REQUIREMENTS
Momentary Overload
IEC 60115-1: 2 x P
r
/10 s for heatsink with
R
th(h-a)
0.26 °C/W (maximum power: 700 W)
1.6 x P
r
/1 s for heatsink with 0.26 °C/W >R
th(h-a)
0.059 °C/W
(maximum power: 1800 W)
± (0.25 % + 0.05 )
Rapid Temperature Change
AEC-Q200 conditions: IEC 60115-1/IEC 60068-2-14, Test Na
50 cycles (- 55 °C to + 200 °C) ± (0.5 % + 0.05 ) for all the ohmic values
1000 cycles (- 55 °C to + 200 °C)
± (5 % + 0.05 ) for R < 38
± (0.5 % + 0.05 ) for R 38
Load Life
AEC-Q200 conditions: IEC 60115-1
2000 h (90/30) P
r
± (5 % + 0.05 ) for R < 38
± (0.5 % + 0.05 ) for R 38
Humidity (Steady State) AEC-Q200 conditions: IEC 60115-1, 1000 h RH 85 %/85 °C ± (0.5 % + 0.05 )
Mechanical Shock
AEC-Q200 conditions: MIL-STD-202 method 213 condition D
(100 g’s/6 ms 3.75 m/s)
± (1 % + 0.05 )
Vibration
AEC-Q200 conditions: MIL-STD-202 method 204 condition D
(5 g, 20 min 10/2000 Hz)
± (1 % + 0.05 )
Climatic Sequence AEC-Q200 conditions: IEC 60115-1 (55/200/56) ± (1 % + 0.05 )
Tightening Torque on Heatsink
LPS 1100
2 Nm
P
T
R
th (j - c)
R
th (c - h)
R
th (h - a)
++
---------------------------------------------------------------------------------------------
=
T 200 °C - 18 °C 182 °C=
R
th (j - c)
R
TH (c - h)
R
TH (h - a)
+
T
P
-------
182
850
----------
0.214 °C/W== =+
R
th (j - c)
0.039 °C/W=
R
th (c - h)
R
th (h - a)
0.214 °C/W - 0.039 °C/W 0.175 °C/W==+
