THS4501CD datasheet(32/48 Pages) NSC

32 / 48 page

0.060

0.040

0.075

0.025

0.205

0.010

vias

Pin 1

Top View

0.017

0.035

0.094

0.030

0.013

DIE

Side View (a)

DIE

End View (b)

Thermal

Pad

Bottom View (c)

THS4500

THS4501

SLOS350F

– APRIL 2002 – REVISED OCTOBER 2011

www.ti.com

the THS4500 family parts directly onto the board.

PowerPAD DESIGN CONSIDERATIONS

The

THS4500

family

available

thermally-enhanced PowerPAD set of packages.

These packages are constructed using a downset

leadframe upon which the die is mounted [see

Figure 112(a) and Figure 112(b)]. This arrangement

results in the lead frame being exposed as a thermal

pad

the

underside

the

package

[see

Figure 112(c)]. Because this thermal pad has direct

thermal contact with the die, excellent thermal

performance can be achieved by providing a good

thermal path away from the thermal pad.

The PowerPAD package allows for both assembly

Figure 113. PowerPAD PCB Etch and Via Pattern

and thermal management in one manufacturing

operation. During the surface-mount solder operation

(when the leads are being soldered), the thermal pad

PowerPAD PCB LAYOUT CONSIDERATIONS

can also be soldered to a copper area underneath the

package. Through the use of thermal paths within this

1. Prepare the PCB with a top side etch pattern as

copper area, heat can be conducted away from the

shown in Figure 113. There should be etch for

package into either a ground plane or other heat

the leads as well as etch for the thermal pad.

dissipating device.

2. Place five holes in the area of the thermal pad.

These holes should be 13 mils (0.33 mm) in

The PowerPAD package represents a breakthrough

diameter. Keep them small so that solder wicking

in combining the small area and ease of assembly of

through the holes is not a problem during reflow.

surface

mount

with

the,

heretofore,

awkward

mechanical methods of heatsinking.

3. Additional vias may be placed anywhere along

the thermal plane outside of the thermal pad

area.

These

holes

help

dissipate

the

heat

generated by the THS4500 family IC. These

additional vias may be larger than the 13-mil

diameter vias directly under the thermal pad.

They can be larger because they are not in the

thermal pad area to be soldered so that wicking

is not a problem.

4. Connect all holes to the internal ground plane.

Figure 112. Views of PowerPAD,

5. When connecting these holes to the ground

Thermally-Enhanced Package

plane, do not use the typical web or spoke via

connection methodology. Web connections have

a high thermal resistance connection that is

Although there are many ways to properly heatsink

useful for slowing the heat transfer during

the PowerPAD package, the following steps illustrate

soldering operations. This transfer slowing makes

the recommended approach.

the soldering of vias that have plane connections

easier. In this application, however, low thermal

resistance is desired for the most efficient heat

transfer. Therefore, the holes under the THS4500

family PowerPAD package should make their

connection to the internal ground plane with a

complete

connection

around

the

entire

circumference of the plated-through hole.

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