10.1 Layout Guidelines
The input capacitors for the DC-DC converters must be placed as close as possible to the VINMAIN, VINCORE, and VCC pins.
- The inductor of the output filter must be placed as close as possible to the device to provide the shortest switch node possible, reducing the noise emitted into the system and increasing the efficiency.
- Sense the feedback voltage from the output at the output capacitors to ensure the best DC accuracy. Feedback must be routed away from noisy sources such as the inductor. If possible, route on the opposite side from the switch node and inductor. Use a GND plane or keep out region to isolate the feedback trace from noisy sources.
- Place the output capacitors as close as possible to the inductor to reduce the feedback loop. This will ensure best regulation at the feedback point.
- Place the device as close as possible to the most demanding or sensitive load. The output capacitors must be placed close to the input of the load. This will ensure the best AC performance possible.
- The input and output capacitors for the LDOs must be placed close to the device for best regulation performance.
- Use vias to connect thermal pad to ground plane.
- TI recommends using the common ground plane for the layout of this device. The AGND can be separated from the PGND, but a large low parasitic PGND is required to connect the PGNDx pins to the CIN and external PGND connections. If the AGND and PGND planes are separated, have one connection point to reference the grounds together. Place this connection point close to the IC.