MIC23303 Datasheet, PDF (16/21 Pages) Micrel Semiconductor – 4MHz PWM 3A Buck Regulator with HyperLight Load™ and Power Good

Micrel, Inc.
MIC23303
Figure 7. PCB Thermal Resistance versus PCB Copper Area
( ) P_DISS
=
^1.8
×
2
×
(1
0.85
− 1)_{}
−
2² × 20mΩ
= 0.56W
The worst case switch and inductor resistance will
increase at higher temperatures, so a margin of 20% can
be added to account for this.
P_DISS = 0.56 × 1.2 = 0.67W
Therefore:
T_J = 0.67W. (61°C/W) + 50°C
T_J = 91°C
This is well below the maximum 125°C.
September 6, 2013
16
090613-2.0