For all switching power supplies, the layout is an important step in the design, especially at high-peak currents and switching frequencies. If the layout is not carefully designed, the regulator might show stability and EMI problems. TI recommends the following PCB layout guidelines for the TPS6514x devices:
An influential component of the thermal performance of a package is board design. To take full advantage of the heat dissipation abilities of the PowerPAD or VQFN package with exposed thermal die, a board that acts similar to a heatsink and allows for the use of an exposed (and solderable) deep downset pad must be used. For further information, see Texas Instruments application notes PowerPAD Thermally Enhanced Package and Power Pad Made Easy. For the VQFN package, see the application report QFN/SON PCB Attachement. Especially for the VQFN package, it is required to solder down the thermal pad to achieve the required thermal resistance.