Optimal dynamic phase add/drop mechanism in multiphase DC-DC buck converters

In multiphase buck converters, phases are dynamically added or dropped based on the output load, to improve efficiency. This is typically achieved by programming a lookup table containing the range of threshold currents for each phase, independent of input voltage and switching frequency. In this work, an algorithm is proposed to recalibrate the threshold currents for operation at optimum number of phases across changes in input voltage and switching frequency. To evaluate the algorithm, a 6-phase synchronous buck converter is tested in forced CCM (Continuous Conduction Mode) over several input voltages and switching frequencies. A maximum efficiency improvement of 1.6% is demonstrated with the proposed algorithm, when compared with the conventional scheme.