THS3110IDRG4 datasheet(22/37 Pages) TI

22 / 37 page

0.205

(5,21)

0.060

(1,52)

0.013

(0,33)

0.017

(0,432)

0.025

(0,64)

0.094

(2,39)

0.040

(1,01)

0.035

(0,89)

0.030

(0,76)

0.075

(1,91)

0.010

vias

(0,254)

DIE

Side View (a)

DIE

End View (b)

Thermal

Pad

Bottom View (c)

THS3110

THS3111

SLOS422E – SEPTEMBER 2003 – REVISED OCTOBER 2009........................................................................................................................................ www.ti.com

PowerPAD DESIGN CONSIDERATIONS

PowerPAD LAYOUT CONSIDERATIONS

1. PCB with a top side etch pattern as shown in

The THS3110 and THS3111 are available in a

Figure 64. There should be etch for the leads as

thermally-enhanced PowerPAD family of packages.

well as etch for the thermal pad.

These packages are constructed using a downset

leadframe upon which the die is mounted (see

Figure 63a and Figure 63b). This arrangement results

in the lead frame being exposed as a thermal pad on

the underside of the package (see Figure 63c).

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. Note that devices such as the

THS311x have no electrical connection between the

PowerPAD and the die.

The PowerPAD package allows for both assembly

and thermal management in one manufacturing

operation. During the surface-mount solder operation

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

can also be soldered to a copper area underneath the

package. Through the use of thermal paths within this

copper area, heat can be conducted away from the

Dimensions are in inches (mm).

package into either a ground plane or other heat

dissipating device.

Figure 64. DGN PowerPAD PCB Etch and

Via Pattern

The PowerPAD package represents a breakthrough

in combining the small area and ease of assembly of

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

surface

mount

with

the,

heretofore,

awkward

These holes should be 0.01 inch (0,254 mm) in

mechanical methods of heatsinking.

diameter. Keep them small so that solder wicking

through the holes is not a problem during reflow.

3. Additional vias may be placed anywhere along

the thermal plane outside of the thermal pad

area. This helps dissipate the heat generated by

the THS3110/THS3111 IC. These additional vias

may be larger than the 0.01-inch (0,254 mm)

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

Figure 63. Views of Thermal Enhanced Package

is not a problem.

4. Connect all holes to the internal ground plane.

Although there are many ways to properly heatsink

Note that the PowerPAD is electrically isolated

the PowerPAD package, the following steps illustrate

from the silicon and all leads. Connecting the

the recommended approach.

PowerPAD to any potential voltage such as VS–,

is acceptable as there is no electrical connection

space

to the silicon.

space

5. When connecting these holes to the ground

plane, do not use the typical web or spoke via

space

connection methodology. Web connections have

space

a high thermal resistance connection that is

useful for slowing the heat transfer during

space

soldering operations. This makes the soldering of

space

vias that have plane connections easier. In this

application, however, low thermal resistance is

space

desired for the most efficient heat transfer.

space

Therefore,

the

holes

under

the

THS3110/THS3111 PowerPAD package should

space

make their connection to the internal ground

plane with a complete connection around the

space

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