The switching node rise and fall times should be minimized for minimum switching loss. Proper layout of the components to minimize high frequency current path loop (see Figure 12-1) is important to prevent electrical and magnetic field radiation and high frequency resonant problems. Follow this specific order carefully to achieve the proper layout.

• Place input capacitor as close as possible to PMID pin and use shortest thick copper trace to connect input capacitor to PMID pin and GND plane.
• It is critical that the exposed thermal pad on the backside of the device be soldered to the PCB ground. Ensure that there are sufficient thermal vias directly under the IC, connecting to the ground plane on the other layers. Connect the GND pins to thermal pad on the top layer.
• Put output capacitor near to the inductor output terminal and the charger device. Ground connections need to be tied to the IC ground with a short copper trace or GND plane
• Place inductor input terminal to SW pin as close as possible and limit SW node copper area to lower electrical and magnetic field radiation. Do not use multiple layers in parallel for this connection. Minimize parasitic capacitance from this area to any other trace or plane.
• Route analog ground separately from power ground if possible. Connect analog ground and power ground together using thermal pad as the single ground connection point under the charger device. It is acceptable to connect all grounds to a single ground plane if multiple ground planes are not available.
• Decoupling capacitors should be placed next to the device pins and make trace connection as short as possible.
• For high input voltage and high charge current applications, sufficient copper area on GND should be budgeted to dissipate heat from power losses.
• Ensure that the number and sizes of vias allow enough copper for a given current path
• See the 2 layer PCB design example in Figure 12-2 for the recommended component placement with trace, grounding and via locations.

Figure 12-1 High Frequency Current Path