10

XLamp Xr-c Leds

trademarks of Cree, Inc.

thermal desiGn

The maximum forward current is determined by the thermal resistance between the LED junction and ambient. Given

an existing thermal resistance of 12 °C/W or 15 °C/W between the junction and the solder point, it is crucial for the end

product to be designed in a manner that minimizes the thermal resistance from the solder point to ambient in order to

optimize lamp life and optical characteristics.

Thermal Design

White, Royal Blue, Blue & Green

0

100

200

300

400

500

600

0

25

50

75

100

125

150

ambient temperature (°c)

Rj-a = 15°C/W

Rj-a = 25°C/W

Rj-a = 35°C/W

Red-Orange, Red

0

100

200

300

400

500

600

700

800

0

25

50

75

100

125

150

ambient temperature (°c)

Rj-a = 20°C/W

Rj-a = 30°C/W

Rj-a = 40°C/W

Amber

0

100

200

300

400

0

25

50

75

100

125

150

ambient temperature (°c)

Rj-a = 20°C/W

Rj-a = 30°C/W

Rj-a = 40°C/W

White

royal blue

blue

Green

amber

red-orange

red