LTC1709-85

The LTC^®1709-85 is a 2-phase, VID programmable, synchronous step-down switching regulator controller that drives two 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 an optimum frequency for efficiency. Thermal design is also simplified.

An operating mode of LTC1709-85 select pin (FCB) can be used to select among three modes including Burst Mode^® operation for highest efficiency. An internal differential amplifier provides true remote sensing of the regulated supply's positive and negative output terminals as required in high current applications.

The RUN/SS pin of LTC1709-85 provides soft-start and optional timed, short-circuit shutdown. Current foldback limits MOSFET dissipation during short-circuit conditions when the overcurrent latchoff is disabled. OPTI-LOOP compensation allows the transient response to be optimized for a wide range of output capacitors and ESR values.