The following filtering circuits are recommended for the power supply inputs listed below.
- VDDA18_Vx1
- VDDA18_FPD
- VDDA18_DSI
- VDDA33_USB
- VDDA18_USB
- VDD_CORE_Vx1
- VDD_CORE_FPD
- VDD_CORE_DSI
- VDD_CORE_USB
Because the PBC layout is critical to the performance of the interfaces associated with these power supplies, it is vital that these power supplies be treated like an analog signal. Specifically:
- Place high-frequency components (such as ferrites and capacitors) as close to the power ball(s) as possible.
- Choose high-frequency ceramic capacitors (such as those with a value of 0.1µF, 0.01µF, and 100nF) that have low ESR and ESL values. Design the leads as short as possible, and as such, it is recommended that these capacitors be placed under the package on the opposite side of the board.
- For each power pin, a single trace (as wide as possible) must be used from the controller to the capacitor and then through the series ferrite to the power source.
- For each power pin, add a 100nF decoupling capacitor placed near the escape via. Add this decoupling capacitance to the capacitance recommended for filters. These are minimum recommendations, so different layouts may require additional capacitance.