11.1 Layout Guidelines

As for all switching power supplies, the layout is an important step in the design. Proper function of the device demands careful attention to PCB layout. Take care in board layout to get the specified performance. If the layout is not carefully done, the regulators may show poor line and/or load regulation, and stability issues, as well as EMI problems. It is critical to provide a low impedance ground path. Therefore, use wide and short traces for the main current paths. The input capacitors must be placed as close as possible to the IC pins as well as the inductor and output capacitor.

For TPS650231RSB, connect the PGND pins of the device to the PowerPAD land of the PCB and connect the analog ground connections (AGND) to the PGND at the PowerPAD. It is essential to provide a good thermal and electrical connection of all GND pins using multiples through to the GND-plane. Keep the common path to the AGND pins, which returns the small signal components, and the high current of the output capacitors as short as possible to avoid ground noise. The VDCDCx line must be connected right to the output capacitor and routed away from noisy components and traces (for example, the L1, L2, and L3 traces).

For TPS650231YFF, connect the PGND pins of the device and the analog ground connections (AGND) to the GND plane on the board. It is essential to provide a good thermal and electrical connection of all GND pins to the GND-plane. Keep the common path to the AGND pins, which returns the small signal components, and the high current of the output capacitors as short as possible to avoid ground noise. The VDCDCx line must be connected right to the output capacitor and routed away from noisy components and traces (for example, the L1, L2, and L3 traces).

11.2 Layout Example

Figure 47. DC–DC Regulator Layout Example