To achieve the levels of high-frequency performance of the THS413x device, follow proper printed-circuit board (PCB) high-frequency design techniques. A general set of guidelines is given below. In addition, a THS413x device evaluation board is available to use as a guide for layout or for evaluating the device performance.
The THS413x is available packaged in a thermally-enhanced DGN package, which is a member of the PowerPAD family of packages. This package is constructed using a downset leadframe upon which the die is mounted (see Figure 45a and Figure 45b). This arrangement results in the lead frame being exposed as a thermal pad on the underside of the package (see Figure 45c). 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 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 package into either a ground plane or other heat dissipating device.
The PowerPAD package represents a breakthrough in combining the small area and ease of assembly of the surface mount with the previously awkward mechanical methods of heatsinking.
More complete details of the PowerPAD installation process and thermal management techniques can be found in the Texas Instruments Technical Brief, (PowerPAD Thermally-Enhanced Package, SLMA002). This document can be found on the TI website (www.ti.com) by searching on the key word PowerPAD. The document can also be ordered through your local TI sales office. Refer to SLMA002 when ordering.