SNVSBY6 October 2021 LM61430-Q1
Like auto mode operation, FPWM mode operation during light load operation is selected as a factory option.
In FPWM mode, frequency is maintained while lightly loaded. To maintain frequency, a limited reverse current is allowed to flow through the inductor. Reverse current is limited by reverse current limit circuitry, see the Electrical Characteristics for reverse current limit values.
For all devices in FPWM mode, frequency reduction is still available if output voltage is high enough to command minimum on time even while lightly loaded, allowing good behavior during faults which involve output being pulled up.