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Forward
Current vs.
Ambient
Temperature
Page 4 of 19
Specifications subject to change without notice.
CLDS-XL7090 - 1104
www.cree.com/xlamp
Thermal Design
The maximum forward current is determined by the thermal resistance between the LED
junction and ambient. Given an existing thermal resistance of 17
°C/W between the
junction and solder point, it is crucial for the application design to minimize the thermal
resistance from solder point to ambient in order to optimize lamp life and optical
characteristics.
0
50
100
150
200
250
300
350
400
0
25
50
75
100
Ambient Temperature (°C)
RθJ-A = 22°C/W
RθJ-A = 50°C/W
RθJ-A = 60°C/W
RθJ-A = 80°C/W
Current derating: Blue/Cyan/Green/White
0
50
100
150
200
250
300
350
400
0
25
50
75
100
Ambient Temperature (°C)
RθJ-A = 20°C/W
RθJ-A = 40°C/W
RθJ-A = 60°C/W
RθJ-A =80°C/W
Current derating: Amber/Red