DCM operation only happens in auto mode when the load current is lower than half of the CCM inductor current ripple, and peak current is higher than I_PEAK-MIN. There is no DCM in FPWM mode. DCM is also known as diode emulation mode. The LS FET is turned off when the inductor current ramps to 0 A. DCM has the same switching frequency as CCM, which is set by the RT pin. Duty cycle and peak current reduces with lighter load in DCM. DCM is more efficient than FPWM under the same condition, because of lower switching losses and lower conduction losses. When the peak current reduces to I_{PEAK_MIN} at lighter load, the LM73605-Q1/6-Q1 in PFM mode.