Specifications
22 Philips Fortimo HBMt Gen 3 System Design In Guide
Figure 23. Interface between module and mounting plate
lled with thermal paste
Figure 24. Label on the Xitanium driver indicates Tcase point
Thermal interfacing
The thermal interface is a critical item for design-in of Fortimo LED HBMt system.
The module’s small area in combination with the relatively high thermal load
translates into high power densities, which increase the impact of the thermal
interface on the total system.
The thermal interface is the interface between the module and the mounting
surface in the luminaire. To ensure good thermal contact, the contact area should
be covered with thermal interface material, e.g. thermal paste, Figure 23.
Around 50 micron thickness of thermal paste, equality spread on the total at
surface of the heatsink is advised.
If the use of thermal paste is not appropriate, and some other thermal interface
material is used (e.g. phase change, graphite, or thermal pad) it is strongly
recommended to follow installation instructions for the selected
interface materials.
Xitanium LED driver temperature
The next key component is the driver, which inuences the lifetime and reliability
of the system. It is important to ensure good thermal and electrical contact
between the driver and the luminaire as this enables the heat to dissipate efciently
and allows the driver to deliver optimal electrical performance. The driver
temperature can be measured with a thermocouple at the Tcase point, shown on
the driver label, Figure 24.
Critical driver temperature point with respect to CLO
When the Fortimo LED High Brightness Module is used with Philips Advance
Xitanium Programmable LED drivers, usage of the CLO feature will increase the
output current. As a result, the driver losses will increase accordingly, which in
turn will lead to a higher driver Tcase temperature. For the thermal design it is
therefore important to ensure that the Tcase temperature of the driver is within
specication for its Tcase max at end of life.
Please refer to individual product datasheets for Tcase information for lifetime.
Warning!
• The use of thermal interface materials other than thermal paste
might require the use of higher efficiency heat sink
• Applying excessive thermal paste does not result in improved
thermal management. For best performance, it is essential to
follow the guidelines above