AB20-4 Datasheet, PDF (1/14 Pages) Lumileds Lighting Company – Thermal Management Considerations for SuperFlux LEDs

application brief AB20 4
replaces AN1149 4
Thermal Management
Considerations for SuperFlux LEDs
Thermal management is critical in the design of LED signal lamps because temperature affects
LED performance and reliability. The following section details the effects of temperature on
LEDs. In addition, thermal measurement techniques of LED signal lamps and recommended
design practices for proper thermal management are covered.
Table of Contents
Importance of Thermal Management
for High-Power LED Assemblies
2
Temperature Induced Effects on LED Light Output
2
Change in Dominant Wavelength (Color) as a Function
Of Junction Temperature
2
Temperature Induced Failures of LEDs
3
Thermal Modeling of LED Assemblies
4
Thermal Resistance of LED Automotive Signal Lamps
4
Junction to Ambient Thermal Resistance Measurement Procedure
5
Junction to Ambient Thermal Resistance Measurement
5
Estimating Junction to Ambient Thermal Resistance
6
Evaluating Junction Temperature and Forward Current
6
Light Output and Forward Current
7
Derating Example Cases
7
Recommended Design Practices for Proper Thermal Management 8
PCB Design
8
Maximum Metallization
8
LED Spacing
9
Lamp Housing Design and Mounting of the LED Array
9
Circuit Design
10
Current Control
10
Power Dissipation
10
“Switching” Power Supplies
11
Ambient Temperature Compensation
11
Appendix 4A
12
Alternate Junction to Ambient Thermal Resistance
Measurement Procedure
12