10.1 Layout Guidelines

1. Locate the VDD capacitor as close as possible between the VDD terminal and GND of the UCCx808-x, tracked directly to both terminals.
2. A small, external filter capacitor is recommended on the CS terminal. Track the filter capacitor as directly as possible from the CS to GND terminal.
3. The tracking and layout of the FB terminal and connecting components is critical to minimizing noise pick-up and interference in the magnetic sensing block. Reduce the total surface area of trances on the FB net to a minimum.
4. The OUTA/OUTB terminal has high internal sink/source current capability. An external gate resistor is recommended. The value depends on the choice of power MOSFET, efficiency and EMI considerations. A pulldown resistor on the gate of the external MOSFET is recommended to prevent the MOSFET gate from floating on if there is an open-circuit error in the gate drive path.

10.2 Layout Example

Figure 9. Layout Example