Application Note
Light Emitting Diode
This sheet contains tentativ e information, we may change contents without notice.
(SP-QR-C-1841A)
Oct. 3, 2013
Heat Dissipation from NC4U13xx depending on Tj
HS-A HS-B HS-C
TS Point
Figure 2 Copper Board
Figure 1
Ts Measuring Point
Front Side
Reverse Surface
HS-A HS-B HS-C
Front Side Reverse Surface
Figure 3 Copper Board & Heat Sink
1. Objective
The light output of LEDs is reduced under the influence of heat generation. When LEDs are operated over the absolute
maximum junction temperature (T
jmax
), the performance is severely degraded. It is critical to design the heat dissipation not to
exceed the T
jmax
for NC4U13xx to achieve a high reliability and a high performance. This document provides the Tj
evaluation results under three conditions by using different heat sinks. Please use the data as reference for NC4U13xx’s
thermal design at your site.
2. Tj Calculation
Tj can be obtained by the following formula:
Tj = Ts + Rthj-s × P
D
where, Tj: Junction Temperatu re [°C]
Ts: Soldering Temperature [°C]
Rthj-s: Thermal resistance between the LED die and the Ts measu ring point [°C/W]
* The Rthj-s of NC4U1 3xx is T yp:1.7 [°C/W] (Max:2.2 [°C/W] )
P
D
: Input Power [W]
3. Tj Measurement Result
Ex. 1 Copper Board + Heat Sink A
I
F
(A) T
S
(
℃
)V
F
(V) T
j
(
℃
)
0.3 70 13.3 77
0.5 93 13.5 104
0.7 117 13.7 133
Ex. 2 Copper Board + Heat Sink B
I
F
(A) T
S
(
℃
)V
F
(V) T
j
(
℃
)
0.3 53 13.4 60
0.5 67 13.7 79
0.7 79 14.0 96
Ex. 3 Copper Board + Heat Sink C
I
F
(A) T
S
(
℃
)V
F
(V) T
j
(
℃
)
0.3 51 13.4 58
0.5 64 13.7 76
0.7 77 14.0 94
4. Heat Dissip ation Materials
- Metal-base d board; Copper , Dimension; 30mm×30mm×1.7mm
- Heat Sink A: 30mm×30mm×h=20mm, Depth: 4mm, Fin; 64 pcs. (Dimension of Fin; 1mm×2mm, St ructure; 8×8)
- Heat Sink B: 50mm×38mm×h=25mm, Depth; 5mm, Fin; 8 pcs. (Dimension of Fin; 1mm×38mm, S tructure; 1×8）
- Heat Sink C: 54mm×54mm×h=35mm, Depth; 4mm, Fin; 64pcs. (Dimension of Fin: 0.8mm×9mm and Structure; 5×13)
Note: Absolute Maximum Ratings
Nichia specifies the absolute maximum ratings for NC4U13xx as I
F=0.7A and T
jmax
=130°C. We cannot assure the
performance of the LEDs if they are used above the specified temperature and I
F. Thank you very much for your
cooperation.