The LTC1709 is a 2-phase, VID programmable, synchronous step-down switching regulator controller that drives all N-channel external power MOSFET stages in a fixed frequency architecture. The 2-phase controller drives its two output stages out of phase at frequencies up to 300kHz to minimize the RMS ripple currents in both input and output capacitors. The 2-phase technique effectively multiplies the fundamental frequency by two, improving transient response while operating each channel at a optimum frequency for efficiency. Thermal design is also simplified.