features, the resulting LTC3733 solution providessuperior performance for a wide range of applications,from enterprise CPU to mobile CPU applications.3-Phase, 65A AMD VRM DesignFigure 1 shows a 3-phase 65A AMD processor powersupply. This supply achieves better than 88% efficiencyfor a 7V input and a 1.55V/65A output, as shown inFigure 2. Even for a 21V input, efficiency peaks at morethan 90%, remaining high throughout a wide 5A to 65Aload range.Figure 3 shows a measured load transient waveform. Theload current step is 46A with a slew rate of 50A/ms. Ten lowprofile Sanyo POSCAP capacitors (330mF/2.5V) are usedon the VRM output. The maximum output voltage varia-tion during the load transients is just 88mVP-P.ConclusionThe LTC3733-based low voltage, high current powersupply meets the AMD processor VRM requirement. With3-phase switching and superior light load operation modes(Stage Shedding and Burst Mode operation), this designcan achieve high efficiency, small size and low overallsolutio LINEAR TECHNOLOGY CORPORATION 2003 dn326f LT/TP 1 Design Note