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LTC3850 - Dual, 2-Phase Synchronous Step-Down Switching Controller

The LTC3850 is a high performance dual synchronous step-down switching regulator controller that drives all N-channel power MOSFET stages. A constant-frequency current mode architecture allows a phase-lockable frequency of up to 780kHz. Power loss and supply noise are minimized by operating the two controller output stages out of phase. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3850 features a precision 0.8V reference and a power good output indicator. A wide 4V to 24V (28V maximum/30V for LTC3850I) input supply range encompasses most battery chemistries and intermediate bus voltages. Independent TK/SS pins for each controller ramp the output voltages 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 and allows the IC to be synchronized to an external clock. The LTC3850 is available in low profile 28-pin 4mm x 4mm, 4mm x 5mm QFN and narrow SSOP packages.

Features Dual, 180° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise High Efficiency: Up to 95% RSENSE or DCR Current Sensing ±1% 0.8V Output Voltage Accuracy Phase-Lockable Fixed Frequency 250kHz to 780kHz Supports Pre-Biased Output Dual N-Channel MOSFET Synchronous Drive Wide VIN Range: 4V to 24V (30V for LTC3850I) Operation Adjustable Soft-Start Current Ramping or Tracking Foldback Output Current Limiting Output Overvoltage Protection Power Good Output Voltage Monitor 28-Pin 4mm × 4mm, 4mm × 5mm QFN and Narrow SSOP Packages Typical Application

Applications Notebook and Palmtop Computers Portable Instruments Battery-Operated Digital Devices DC Power Distribution Systems Packaging

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