Out-of-Audio (OOA) light-load mode is a unique control feature that keeps the switching frequency above audible frequency with minimum reduction in efficiency. It prevents audio noise generation from the output capacitors and inductor. During Out-of-Audio operation, the OOA control circuit monitors the states of both high-side and low-side MOSFETs and forces them to switch. When both high-side and low-side MOSFETs are off for more than 30 μs during a light-load condition, the low-side FET will discharge until output voltage drops to trigger the high-side FET on or inductor current hits negative OC limit.

If the MODE pin is selected to operate in OOA mode, when the device works at light load, the minimum switching frequency is above 20 kHz which avoids the audible noise in the system. When the device works in OOA mode, TI recommends setting the peak value of inductor current above –1 A by choosing appropriate inductor.