This pin monitors the boost input voltage to determine if the level is correct to allow the boost circuit to switch. When the boost circuit is used, the BIN signal usually originates from the rectified and filtered Auxiliary voltage.
- Place the AUX voltage rectifier and main filter capacitor (CBIN1) near the transformer pins to minimize the AUX switching current loop. Return that capacitor's negative lead directly back to the transformer pin. Then run the negative track to the BGND pin and the positive net to the boost inductor input.
- Place another filtering capacitor (CBIN2) at the input to the boost inductor and return that negative lead directly to the BGND pin to minimize boost switching current loop area.
- Connect the BIN pin to (CBIN2) at the input of the boost inductor.
If the boost circuit is not used, connect BIN directly to BGND.