Texas Instruments TPS54810 - Manual (Page 11)

TPS54810
SLVS420B − MARCH 2002 − R EVISED FEBRUARY 2005
www.ti.com
11
LAYOUT CONSIDERATIONS FOR THERMAL
PERFORMANCE
For operation at full rated load current, the analog ground
plane must provide adequate heat dissipating area. A 3
inch by 3 inch plane of 1 ounce copper is recommended,
though not mandatory, depending on ambient temperature
and airflow. Most applications have larger areas of internal
ground plane available, and the PowerPAD should be
connected to the largest area available. Additional areas
on the top or bottom layers also help dissipate heat, and
any area available should be used when 8 A or greater
operation is desired. Connection from the exposes area of
the PowerPAD to the analog ground plane layer should be
made using 0.013 inch diameter vias to avoid solder
wicking through the vias. Eight vias should be in the
PowerPAD area with four additional vias located under the
device package. The size of the vias under the package,
but not in the exposed thermal pad area, can be increased
to 0.018. Additional vias beyond the twelve recommended
that enhance thermal performance should be included in
areas not under the device package.
Connect Pin 1 to Analog Ground Plane
in This Area for Optimum Performance
Minimum Recommended Top
Side Analog Ground Area
0.3478
0.0150
0.06
0.0256
0.1700
0.1340
0.0630
0.0400
Ø0.0180 4 PL
0.2090
Ø0.0130 8 PL
Minimum Recommended Exposed
Copper Area for Powerpad. 5-mil
Stencils May Require 10 Percent
Larger Area
0.0650
0.0500
0.0500
0.0650
0.0339
0.0339
0.0500
Minimum Recommended Thermal Vias: 8 x 0.013 Diameter Inside
Powerpad Area 4 x 0.018 Diameter Under Device as Shown.
Additional 0.018 Diameter Vias May Be Used if Top Side Analog Ground
Area Is Extended.
0.3820
Figure 11. Recommended Land Pattern for the 28−Pin PWP PowerPAD