Datasheet

3333
Copyright © 2013-2015 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree
®
, the Cree logo, XLamp
®
and EasyWhite
®
are
registered trademarks of Cree, Inc. UL
®
and the UR logo are registered trademarks of UL LLC.
33
XLamp
®
CXa1304 LED
THERMAL DESIGN
The CXA 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 has intentionally removed junction-temperature-based operating limits and
replaced the commonplace maximum T
J
calculations with maximum ratings based on forward current (I
F
) and case
temperature (Tc). No additional calculations are required to ensure the CXA LED is being operated within its designed
limits. Please refer to page 2 for the Operating Limit specication.
There is no need to calculate for T
J
inside the package, as the thermal management design process, specically from
solder point (T
SP
) to ambient (T
a
), remains identical to any other LED component. For more information on thermal
management of Cree XLamp LEDs, please refer to the Thermal Management application note. For CXA soldering
recommendations and more information on thermal interface materials (TIM) and connection methods, please refer
to the Cree XLamp CX Family LEDs soldering and handling document. The CX Family LED Design Guide provides basic
information on the requirements to use Cree XLamp CXA LEDs successfully in luminaire designs.
To keep the CXA1304 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 each graph is a base 10 logarithmic scale.
As the gure 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
CXA1304-9V
0.01
0.10
1.00
10.00
100.00
200 300 400 500 600 700 800 900 1000
Maximum R_c-a
Current (mA)
Ta = 25 °C
Ta = 55 °C
Ta = 85 °C
Ta = 105 °C
9 V