LPS 1100

www.vishay.com

Vishay Sfernice

Revision: 05-Sep-12

2

Document Number: 50059

THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT

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.

resistance of the component: 0.039 °C/W.

thermal resistance of the interface (grease, thermal pad), and the quality of the fastening device.

Example:

PERFORMANCE

TESTS

CONDITIONS

REQUIREMENTS

Momentary Overload

(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 U

± (0.5 % + 0.05

) for R  38 U

Load Life

AEC-Q200 conditions: IEC 60115-1

± (5 % + 0.05

) for R < 38 U

± (0.5 % + 0.05

) for R  38 U

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

==

+