SWITCHMODE™ Power Supply Reference Manual

SMPSRMInterleaved Multiphase ConvertersOne method of increasing the output power of anytopology and reducing the stresses upon thesemiconductors, is a technique called interleaving. Anytopology can be interleaved. An interleaved multiphaseconverter has two or more identical converters placed inparallel which share key components. For an n–phaseconverter, each converter is driven at a phase differenceof 360/n degrees from the next. The output current fromall the phases sum together at the output, requiring onlyI out /n amperes from each phase.The input and output capacitors are shared among thephases. The input capacitor sees less RMS ripple currentbecause the peak currents are less and the combined dutycycle of the phases is greater than it would experiencewith a single phase converter. The output capacitor canbe made smaller because the frequency of currentwaveform is n–times higher and its combined duty cycleis greater. The semiconductors also see less currentstress.A block diagram of an interleaved multiphase buckconverter is shown in Figure 13. This is a 2–phasetopology that is useful in providing power to a highperformance microprocessor.++–V FDBKControlGNDC FAV IN C IN+S A1L AGATEA1GATEA2GATEB2GATEB1S A2S B1L B+C OUT V OUT–C FBCS5308S B2Voltage FeedbackCurrent Feedback ACurrent Feedback BFigure 13. Example of a Two–Phase Buck Converter with Voltage and Current Feedbackhttp://onsemi.com13