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.
It is critical to provide a low-inductance, low-impedance ground path. Therefore, use wide and short traces for the main current paths as indicated in bold in Figure 11-1.
Place the input capacitor as close as possible to the IC pins VIN and GND, the inductor and output capacitor as close as possible to the pins SW1 and GND.
Connect the GND pin of the device to the PowerPAD of the PCB and use this pad as a star point. For each converter, use a common power GND node and a different node for the signal GND to minimize the effects of ground noise.
Connect these ground nodes together to the PowerPAD (star point) underneath the IC. Keep the common path to the GND PIN, which returns the small signal components and the high current of the output capacitors, as short as possible to avoid ground noise.
Connect the output voltage-sense lines (FB 1, DEF_1, ADJ2) right to the output capacitor and route them away from noisy components and traces (for example, the SW1 and SW2 lines).
If operating the EasyScale interface with high transmission rates, route the MODE/DATA trace away from the ADJ2 line to avoid capacitive coupling into the ADJ2 pin.
A GND guard ring between the MODE/DATA pin and ADJ2 pin avoids potential noise coupling.