The max frequency depends on the load conditions and propagation delays.
The max DOI to DOI_LVL propagation delay is 8us which corresponds to 12.5kHz.
In the datasheet we spec the REGIN Current and V5 current for PP Mode at 10kHz switching conditions.
The DO HS switching frequency depends on the load conditions, especially for the inductive load. Usually it does not exceed 1kHz for small inductors and in 1~10Hz range for 1.5~1H inductors.