Datasheet

13mils(0.33mm)
Package
ThermalPad
Component
Traces
ThermalVia
Component(top)Side
GroundPlane
PowerPlane
Solder(bottom)Side
ThermalIsolation
(powerplaneonly)
Package
ThermalPad
(bottomtrace)
ADS1274
ADS1278
www.ti.com SBAS367F –JUNE 2007– REVISED FEBRUARY 2011
PowerPAD PCB Layout Considerations
The via connections to the thermal pad and internal
ground plane should be plated completely around the
Figure 92 shows the recommended layer structure for
hole, as opposed to the typical web or spoke thermal
thermal management when using a PowerPad
relief connection. Plating entirely around the thermal
package on a 4-layer PCB design. Note that the
via provides the most efficient thermal connection to
thermal pad is placed on both the top and bottom
the ground plane.
sides of the board. The ground plane is used as the
heatsink, while the power plane is thermally isolated
Additional PowerPAD Package Information
from the thermal vias.
Texas Instruments publishes the PowerPAD
Figure 93 shows the required thermal pad etch
Thermally Enhanced Package Application Report (TI
pattern for the HTQFP-64 package used for the
literature number SLMA002), available for download
ADS1274. Nine 13mil (0.33mm) thermal vias plated
at www.ti.com, that provides a more detailed
with 1 ounce of copper are placed within the thermal
discussion of PowerPAD design and layout
pad area for the purpose of connecting the pad to the
considerations. Before attempting a board layout with
ground plane layer. The ground plane is used as a
the ADS1274, it is recommended that the hardware
heatsink in this application. It is very important that
engineer and/or layout designer be familiar with the
the thermal via diameter be no larger than 13mils in
information contained in this document.
order to avoid solder wicking during the reflow
process. Solder wicking results in thermal voids that
reduce heat dissipation efficiency and hampers heat
flow away from the IC die.
Figure 92. Recommended PCB Structure for a 4-Layer Board
© 2007–2011, Texas Instruments Incorporated Submit Documentation Feedback 41
Product Folder Link(s): ADS1274 ADS1278