Dual-phase buck controller for high-current POL rails
The LTC3774IUHE#PBF is a dual-output, dual-phase step-down PWM controller from the PolyPhase series, designed for non-isolated point-of-load regulators that need to share current across two interleaved phases. It drives external N-channel MOSFETs and generates a PWM signal for each phase, reducing input ripple and allowing smaller input capacitors compared to a single-phase design. Control features include current limit, enable, frequency control, power good, soft start, and output tracking — enough to sequence multiple rails without an external supervisor.
The 98% maximum duty cycle keeps the high-side FET on nearly the whole cycle, useful when the input voltage is only slightly above the output target. No synchronous rectifier is built in; the external MOSFETs handle the low-side switching, so the designer chooses the FETs for the target efficiency and thermal budget. The pad is the main thermal path — a layout review is worth the time.