The BSW pin is the drain of the internal boost switch and carries high-frequency switching current internally to BGND. To avoid self-generated noise and interference with control signals, minimize the boost switching current loop area.
- Place the boost inductor (LB) close to the controller to minimize the track length from the inductor output to the BSW pin. To avoid inducing switching noise into control signals, do not run such signal tracks over, under, or through the boost switching loop.
- Place the boost output diode (DB) at the output of the boost inductor is such a way that minimized the loop area with the boost output filter capacitor (CVDD1) and return that capacitor's negative lead directly to the BGND pin to minimize boost switching current loop area.
If the boost circuit is not used, connect BSW directly to BGND.