SLUSDF9 June 2020 BQ25790
In order to improve converter light-load efficiency, the device switches to PFM control at light load condition. The effective switching frequency decreases accordingly as load current decreases. The PFM operation can be disabled by setting PFM_FWD_DIS = 1, the converter stays at the PWM mode switching frequency and go to DCM operation at light load condition. The minimum effective switching frequency in PFM can be limited to 25 kHz to eliminate the audible noise concern if the out of audio (OOA) feature is enabled by setting DIS_FWD_OOA = 0. The host can disable the OOA by setting DIS_FWD_OOA = 1, which may result in the converter effective switching frequency dropping below 25 kHz at extremely light load.