8.4.5 Light Load Operation

When the load current is lower than half of the peak-to-peak inductor current in CCM, the LM43600 operates in discontinuous conduction mode (DCM), also known as diode emulation mode (DEM). In DCM operation, the LS FET is turned off when the inductor current drops to 0 A to improve efficiency. Both switching losses and conduction losses are reduced in DCM, comparing to forced PWM operation at light load.

At even lighter current loads, pulse frequency mode (PFM) is activated to maintain high efficiency operation. When the HS switch ON-time reduces to T_{ON_MIN} or peak inductor current reduces to its minimum I_PEAK-MIN, the switching frequency will reduce to maintain proper regulation. Efficiency is greatly improved by reducing switching and gate drive losses.