7.4.3 Out of Audio Mode

Out-of-Audio (OOA) light-load mode is a unique control feature that keeps the switching frequency above audible frequency towards a virtual no-load condition. During Out-of-Audio operation, the OOA control circuit monitors the states of both high-side and low-side MOSFETs and forces them switching if both MOSFETs are off for more than 28 μs. When both high-side and low-side MOSFETs are off for more than 28 μs during a light-load condition, the lowside FET will be on for discharge till reverse OC happens or output voltage drops to trigger the high-side FET on. This mode initiates one cycle of the low-side MOSFET and the high-side MOSFET turning on. Then, both MOSFETs stay turned off waiting for another 28 μs.

If the MODE pin is selected to operate in OOA mode, when the device works at light load, the minimum switching frequency is above 25 kHz which avoids the audible noise in the system.