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 V_IN Range: 4V to 30V Operation
• Adjustable Soft-Start Current Ramping or Tracking
• Foldback Output Current Limiting
• Output Overvoltage Protection
• Power Good Output Voltage Monitor
• 28-Pin Narrow SSOP Package

Typical Application

Description

The LTC3850-2 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 LTC3850-2 features a precision 0.8V reference and a power good output indicator. A wide 4V to 30V 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 LTC3850-2 is identical to the LTC3850-1, except they have different pin assignments.