The LTC3851A is a high performance synchronous step-down switching regulator controller that drives an all N-channel synchronous power MOSFET stage. A constant frequency current mode architecture allows a phase-lockable frequency of up to 750kHz.OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3851A features a precision 0.8V reference that is compatible with a wide 4V to 38V input supply range.The TK/SS pin ramps the output voltage during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The MODE/PLLIN pin selects among Burst Mode operation, pulse-skipping mode or continuous inductor current mode at light loads and allows the IC to be synchronized to an external clock. The LTC3851A contains an improved PLL compared to the LTC3851.The LTC3851A-1 is a version with a power good output signal instead of adjustable current limit.FeaturesLTC3851Not Recommended For New DesignsLTC3851-1Not Recommended For New DesignsLTC3851AAdjustable Current LimitLTC3851A-1PGOOD OutputAPPLICATIONSAutomotive SystemsTelecom SystemsIndustrial EquipmentDistributed DC Power Systems