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LTC3853 - Triple Output, Multiphase Synchronous Step-Down Controller

The LTC®3853 is a high performance triple output stepdown switching regulator controller that drives all Nchannel synchronous power MOSFET stages. Power loss and supply noise are minimized by operating the output stages out of phase. The part can be configured as a dual phase controller plus a single phase controller if needed. The part can also be configured to provide a single 3-phase output for even higher output currents.

A wide 4.5V to 24V (28V maximum) input voltage supply range encompasses most battery chemistries and intermediate bus voltages. Phase 3 can regulate output voltages up to 13.5V. A constant-frequency current mode architecture allows for a phase-lockable frequency up to 750kHz.

Independent TK/SS pins for each output ramps the output voltages and can be configured for coincident or ratiometric tracking. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The MODE/PLLIN pin selects among Burst Mode® operation, pulse-skipping or continuous inductor current modes.

Features Triple, 120° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise Configurable as a 180° Dual Phase Controller Plus a Single Phase Controller The Third Phase Can Regulate Up to a 13.5V Output High Efficiency: Up to 92% RSENSE or DCR Current Sensing ±0.75% 0.8V Output Voltage Accuracy Phase-Lockable Fixed Frequency 250kHz to 750kHz Supports Pre-Biased Outputs Dual N-Channel MOSFET Synchronous Drive Wide VIN Range: 4.5V to 24V Operation (28V Abs Max) Adjustable Soft-Start Current Ramping or Tracking Foldback Output Current Limiting Output Overvoltage Protection Dual Power Good Output Voltage Monitors 40-Lead 6mm × 6mm QFN Package Typical Application

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