IW3612 Datasheet, PDF (14/18 Pages) Dialog Semiconductor – AC/DC Digital Power Controller for Dimmable LED Drivers

iW3612
AC/DC Digital Power Controller for
Dimmable LED Drivers
be electrically connected to the GND pin of the IC. Although
by having an exposed package can provide some thermal
resistance improvement, more significant improvements can
be obtained with simple PCB layout and design. Figure 9.14
demonstrates some recommended techniques to improve
thermal resistance, which are also highlighted below.
Ways to Improve Thermal Resistance
●● Increase PCB area and associated amount of copper
interconnect.
●● Use thermal adhesive to attach the package to a thermal
pad on PCB.
●● Connect PCB thermal pad to additional copper on PCB
using thermal vias.
Environment
No adhesive
Use thermal adhesive to pad
Use thermal adhesive to pad with thermal vias
ψ_JB
70 °C/W
63 °C/W
49 °C/W
Table 9.1 : Improvements in ψ_JB Based on Limited
Experimentation
Effect of Thermal Resistance Improvements
85
75
A
65
~ 30%
55
B
45
35
25
5
10
15
20
25
30
PCB Area (cm²)
A: without thermal adhesive and thermal vias
B: with thermal adhesive and thermal vias
Figure 9.15 : Effect of Thermal Resistance Improvements
Figure 9.15 shows improvement of approximately 30% in
thermal resistance across different PCB sizes when the
exposed pad is attached to PCB using a thermal adhesive
and thermal vias connect the pad to a larger plate on the
opposing side of the PCB.
Rev. 1.6
iW3612

Page 14