SLUSEK7 September 2024 BQ25773
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
The BQ25773 input current sensing through ACP_A-ACN_A and ACP_B-ACN_B are critical to ensure IINDPM/IOTG regulation stability. Parasitic inductance on board will generate high frequency ringing on ACP_A-ACN_A and ACP_B-ACN_B which overwhelms converter sensed inductor current information. Larger parasitic inductance will generate larger sense current ringing which could cause the average current control loop to go into oscillation. Therefore ACP_A-ACN_A and ACP_B-ACN_B sensing information need to be conditioned.
For real system board condition, we suggest using below circuit design to get best result and filter noise induced from different PCB parasitic factor. The filter is effective and the delay of on the sensed signal is small, therefore there is no concern for average current mode control. On ACN_A and ACN_B side the maximum capacitance is 1*10-μF MLCC shown below, the 10 nF + 1 nF EMI filtering capacitance can be neglected comparing to the 10-μF MLCC. When the 10-μF MLCC is used on ACN_A and ACN_B, then differential 100-nF ~ 220-nF filter capacitors are recommended for ACP_A-ACN_A and ACP_B-ACN_B to prevent pulse reverse current through RAC.