Features

• Dual, 180° Phased Controllers Reduce Required
• Input Capacitance and Power Supply Induced Noise
• High Efficiency: Up to 95%
• R_SENSE 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

Description

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.