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The LM2639 provides an attracTIve soluTIon for power supplies of high power microprocessors (such as PenTIum II™,M II™, K6™-2, K6™-3, etc.) exhibiTIng ultra fast load transients.Compared to a conventional single-phase supply, anLM2639 based multi-phase supply distributes the thermaland electrical loading among components in multiple phasesand greatly reduces the corresponding stress in each component.The LM2639 can be programmed to control either a3-phase converter or a 4-phase converter. Phase shiftamong the phases is 120° in the case of three phase and 90°with four-phase. Because the power channels are out ofphase, there can be significant ripple cancellation for boththe input and output current, resulting in reduced input andoutput capacitor size. Due to the nominal operating frequencyof 2 MHz per phase, the size of the output inductorscan be greatly reduced which results in a much faster loadtransient response and a dramatically shrunk output capacitorbank. Microprocessor power supplies with all surface mount components can be easily built.
