A system level solution to improve VRM efficiency

An investigation of the synchronous buck regulator working as a voltage regulator module (VRM) for processor power supply applications, under light load condition is presented. VRM, a very special case of power supply belongs to switched mode power supply family. Important design specifications include low output voltage with extremely small tolerance band, high load current of large slew rates, small foot print, low cost etc. Higher operating efficiencies are desired to enable extended battery mode operation in mobile platforms in addition to reducing heat dissipation. This paper identifies the source of energy inefficiency and suggests a variable frequency approach as a cost effective system level solution, to enhance the efficiency of the converter supplying widely varying load with special emphasis to light load operation.