TSB81BA3IPFPEP datasheet(24/61 Pages) TI1

24 / 61 page

TSB81BA3D, TSB81BA3DI

IEEE 1394b THREE-PORT CABLE TRANSCEIVER/ARBITER

SLLS559E − DECEMBER 2002 − REVISED JUNE 2006

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

APPLICATION INFORMATION

designing with PowerPAD

™

The TSB81BA3D is housed in a high performance, thermally enhanced, 80-terminal PFP PowerPAD

™

package. Use of the PowerPAD package does not require any special considerations except to note that the

PowerPAD, which is an exposed die pad on the bottom of the device, is a metallic thermal and electrical

conductor. Therefore, if not implementing PowerPAD PCB features, the use of solder masks (or other assembly

techniques) may be required to prevent any inadvertent shorting by the exposed PowerPAD of connection

etches or vias under the package. The recommended option, however, is to not run any etches or signal vias

under the device, but to have only a grounded thermal land as explained below. Although the actual size of the

exposed die pad may vary, the maximum size required for the keepout area for the 80-terminal PFP PowerPAD

package is 10 mm

× 10 mm. The actual PowerPAD size for the TSB81BA3D is 6 mm × 6 mm.

It is recommended that there be a thermal land, which is an area of solder-tinned-copper, underneath the

PowerPAD package. The thermal land varies in size, depending on the PowerPAD package being used, the

PCB construction, and the amount of heat that needs to be removed. In addition, the thermal land may or may

not contain numerous thermal vias depending on PCB construction.

Other requirements for thermal lands and thermal vias are detailed in the TI application note PowerPAD

™

Thermally Enhanced Package Application Report, (SLMA002), available via the TI Web pages at URL:

http://www.ti.com.

Figure 9. Example of a Thermal Land for the TSB81BA3D PHY

For the TSB81BA3D, this thermal land must be grounded to the low impedance ground plane of the device. This

improves not only thermal performance but also the electrical grounding of the device. It is also recommended

that the device ground terminal landing pads be connected directly to the grounded thermal land. The land size

must be as large as possible without shorting device signal terminals. The thermal land may be soldered to the

exposed PowerPAD using standard reflow soldering techniques.

While the thermal land may be electrically floated and configured to remove heat to an external heat sink, it is

recommended that the thermal land be connected to the low impedance ground plane for the device. More

information may be obtained from the TI application note PHY Layout, (SLLA020).

PowerPAD is a trademark of Texas Instruments.

TSB81BA3IPFPEP Datasheet(PDF) 24 Page - Texas Instruments