Multi-mode works in the following manner. All modes work the same when the load current is moderate to full. The difference comes when the load current is reduced to less than half of the inductor current ripple value. The PWM Continuous Conduction Mode (or CCM) allows the inductor current to go negative, thus keeping the converter in PWM which is a constant frequency operation. This mode allows the converter to respond quickly to any load changes, even down to zero load, and also keeps the output voltage ripple to a minimum. The PWM Discontinuous Conduction Mode (or DCM) turns off the synchronous rectification FET (shown as S2 in the figure) when the induction current begins to go in a negative direction. This mode saves the power dissipation by the inductor negative current, improving the converter efficiency during this light load condition. In addition to preventing the inductor negative current, PFM, or Pulse Frequency Modulation, also skips several pulses of the switching cycle to save the FET’s switching losses. This mode offers the highest light load efficiency, but sacrifices with a slightly higher output voltage ripple. Unique to Analog Devices' Himalaya, during the skipping period, the IC enters hibernation where it turns off un-utilized internal circuitries, hence achieving the best possible efficiency.