XLAMP® CHA0612 LED

© 2022 Cree LED. The information in this document is subject to change without notice. Cree® and the Cree logo are registered trademarks, and the

Cree LED logo is a trademark, of Wolfspeed, Inc. XLamp® and EasyWhite® are registered trademarks of Cree LED.

CLD-DS268

REV 0

21

THERMAL DESIGN

The CHA family of LED arrays can include over a hundred different LED die inside one package, and thus over a hundred different junction

temperatures (T

J). Cree LED has intentionally removed junction-temperature-based operating limits and replaced the commonplace

maximum T

J calculations with maximum ratings based on forward current (IF) and case temperature (Tc). No additional calculations

are required to ensure the CHA LED is being operated within its designed limits. LES temperature measurement provides additional

verification of good thermal design. Please refer to page 3 for the Operating Limits specification.

There is no need to calculate for T

J inside the package, as the thermal management design process, specifically from solder point (TSP) to

ambient (T

a), remains identical to any other LED component. For more information on thermal management of XLamp LEDs, please refer

to the Thermal Management application note. For CHA soldering recommendations and more information on thermal interface materials

(TIM), LES temperature measurement, and connection methods, please refer to the XLamp CHA Family LEDs soldering and handling

document.

To keep the CHA0612 LED at or below the maximum rated Tc, the case to ambient temperature

thermal resistance (R_c-a) must be at or below the maximum R_c-a value shown on the following

graphs, depending on the operating environment. The y-axis in the graphs is a base 10 logarithmic

scale.

As the figure at right shows, the R_c-a value is the sum of the thermal resistance of the TIM (R_tim)

plus the thermal resistance of the heat sink (R_hs).

R_j-c

Tc

R_tim

R_hs

Ta

R_j-c

Tc

R_c-a

Ta

CHA0612 18V

0.01

0.10

1.00

10.00

100.00

100

200

300

400

500

600

700

800

900

1000

1100

1200

Current (mA)

Ta = 25 °C

Ta = 55 °C

Ta = 85 °C

Ta = 105 °C

18 V