SLUAAN2 april 2023 TPS543620 , TPS54620 , TPS54J060 , TPS54J061 , TPS566231 , TPS566235 , TPS566238 , TPS566242 , TPS566247
In the applications where Vout is close to Vin, large duty is needed to support normal regulation. Due to minimum off-time limit, if switching frequency does not change, the maximum duty-cycle is fixed. Large Duty Operation extends the high-side FET on-time, thus decreasing switching frequency and allowing large duty cycles to be maintained. The Large Duty Cycle Operation With the TPS568230 application note describes the details.
Some parts support 100% duty-cycle mode, high-side FET is continuously switched on as long as the BOOT capacitor voltage is higher than preset UVLO threshold.