10.1 Layout Guidelines

The TPA3111D1-Q1 device can be used with a small, inexpensive ferrite bead output filter for most applications. However, because the Class-D switching edges are very fast, carefully planning the layout of the printed circuit board is important. Use the guidelines that follow to help meet the EMC requirements:

• The high-frequency decoupling capacitors should be placed as close to the PVCC and AVCC pins as possible. Large (220 μF or greater) bulk power-supply decoupling capacitors should be placed near the TPA3111D1-Q1 device on the PVCC supplies. Local, high-frequency bypass capacitors should be placed as close to the PVCC pins as possible. These capacitors can be connected to the thermal pad directly for an excellent ground connection. Consider adding a small, good-quality low-ESR ceramic capacitor with a value between 220 pF and 1000 pF and a larger good-quality mid-freqency capacitor with a value between 0.1 µF and 1 µF to the PVCC connections at each end of the chip.
• Keep the current loop from each of the outputs through the ferrite bead and the small filter cap and back to PGND as small and tight as possible. The size of this current loop determines its effectiveness as an antenna.
• The ferrite EMI filter (Figure 19) should be placed as close to the output pins as possible for the best EMI performance. The LC filter (Figure 17 and Figure 18) should be placed close to the outputs. The capacitors used in both the ferrite and LC filters should be grounded to power ground.
• The thermal pad must be soldered to the PCB for proper thermal performance and optimal reliability. The dimensions of the thermal pad and thermal land should be 6.46 mm by 2.35 mm. Seven rows of solid vias (three vias per row, 0.33 mm or 13 mils diameter) should be equally spaced underneath the thermal land. The vias should connect to a solid copper plane, either on an internal layer or on the bottom layer of the PCB. The vias must be solid vias, not thermal relief or webbed vias. See PowerPAD™ Thermally Enhanced Package (SLMA002) for more information on using the thermal pad of the package. For recommended PCB footprints, see the mechanical pages in the Mechanical, Packaging, and Orderable Information section.

10.2 Layout Example

Figure 21. Recommended Layout