TPS54980

SLVS452A − FEBRUARY 2003 − REVISED FEBRUARY 2005

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11

LAYOUT CONSIDERATIONS FOR THERMAL

PERFORMANCE

For operation at full rated load current, the analog ground

plane must provide an 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 must be

connected to the largest area available. Additional areas

on the top or bottom layers also help dissipate heat, and

any area available must be used when 9 A or greater

operation is desired. Connection from the exposed area of

the PowerPAD to the analog ground plane layer must be

made using 0.013 inch diameter vias to avoid solder

wicking through the vias. Eight vias must 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 must 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

Ø 0.0180

4 PL

0.2090

Ø 0.0130

8 PL

Minimum Recommended Exposed

Copper Area for Powerpad. 5mil

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 28-Pin PWP PowerPAD