PLW114050 Datasheet, PDF (1/3 Pages) List of Unclassifed Manufacturers – MAGIC LED

MAGIC LED PLW114050 Series
Application Note
Thermal Management
Solid-state light emitting diodes (LED) are highly efficient and reliable when
compared with traditional light source technologies. Their long-term reliability
performance depends highly on maintaining the operating conditions within the
datasheet recommendations. Although today LEDs are very efficient, a considerable
amount of the electrical input power is still not converted into light but simply lost and
transformed into heat. Unfortunately, the heat generated inside the LED impacts
negatively on its performance and in extreme cases can even cause catastrophic
failure. The LEDs are designed to dissipate heat efficiently but users need to make
sure the LEDs are operating within specification. The performance of Plessey LED
is characterized versus its junction temperature Tj. The junction temperature can not
be measured directly and therefore it is calculated using equation (1) below;
Tj= Ta + (Rө j-sp + Rө sp-hs + Rө hs-a) * (Vf * If – Wop)
(1)
Where,
Tj is the junction temperature in degrees Celsius (°C)
Ta is the ambient temperature (°C)
Rө j-sp is the thermal resistance between junction and solder point (°C/W)
Rө sp-hs is the thermal resistance of the PCB heat sink (°C/W)
Rө hs-a is the thermal resistance between PCB heat sink and ambient (°C/W)
If is the forward current and Vf is forward voltage.
Wop is the optical radiant power (W).
Therefore, a good thermal dissipation design consists of minimizing both thermal
resistances RÓ© sp-hs and RÓ© hs-a achieved by optimising the heat conduction path.
PLESSEY| TAMERTON ROAD | ROBOROUGH | PLYMOUTH | DEVON | PL6 7BQ
Phone: [phone]
Fax: [phone]
Web: www.plesseysemi.com
Datasheet No 292552 Issue 1
Page 1 of 3