10.1 Layout Guidelines
Because the class-D switching edges are fast, it is necessary to take care when planning the layout of the printed circuit board. The following suggestions help to meet EMC requirements.
- Decoupling capacitors — The high-frequency decoupling capacitors should be placed as close to the PVCC and AVCC terminals as possible. Large (100 μF or greater) bulk power supply decoupling capacitors should be placed near the TPA3116D2-Q1 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 IC GND pad directly for an excellent ground connection. Consider adding a small, good-quality, low-ESR ceramic capacitor between 220 pF and 1 nF and a larger mid-frequency capacitor of value between 100 nF and 1 µF, also of good quality, to the PVCC connections at each end of the chip.
- Keep the current loop from each of the outputs through the filter and back to GND as small and tight as possible. The size of this current loop determines its effectiveness as an antenna.
- Grounding — The PVCC decoupling capacitors should connect to GND. All ground should be connected at the IC GND, which should be used as a central ground connection or star ground for the TPA3116D2-Q1.
- Output filter — The LC filter should be placed close to the outputs. The capacitor used in the LC filter should be grounded.
For an example layout, see the TPA3116D2 Evaluation Module (TPA3116D2EVM) User Guide (SLOU336). Both the EVM user manual and the thermal pad application reports, SLMA002 and SLMA004, are available on the TI Web site at http://www.ti.com.
10.3 Heat Sink Used on the EVM
The heat sink (part number ATS-TI 10 OP-521-C1-R1 or equivalent) used on the EVM is a 14-mm × 25-mm × 50-mm extruded aluminum heat sink with three fins (see Figure 24). For additional information on the heat sink, go to www.qats.com.
Figure 24. EVM Heatsink
This size heat sink has shown to be sufficient for continuous output power. The crest factor of music and having airflow lowers the requirement for heat sinking, and smaller types of heat sinks can be used.