Features

• Dual, 180° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
• High Efficiency: Up to 95%
• RSENSE or DCR Current Sensing
• Programmable DCR Temperature Compensation
• ±0.75% 0.6V Output Voltage Accuracy
• Phase-Lockable Fixed Frequency 250kHz to 770kHz
• True Remote Sensing Differential Amplifier
• Dual N-Channel MOSFET Synchronous Drive
• Wide V_IN Range: 4.5V to 38V
• V_OUT Range: 0.6V to 12.5V without Differential Amplifier
• V_OUT Range: 0.6V to 3.3V with Differential Amplifier
• Clock Input and Output for Up to 12-Phase Operation
• Adjustable Soft-Start or V_OUT Tracking
• Foldback Output Current Limiting
• Output Overvoltage Protection
• 40-Pin (6mm × 6mm) QFN and 38-Lead FE Packages

Typical Application

Description

The LTC3855 is a dual PolyPhase current mode synchronous step-down switching regulator controller that drives all N-channel power MOSFET stages. It includes a high speed differential remote sense amplifier. The maximum current sense voltage is programmable for either 30mV, 50mV or 75mV, allowing the use of either the inductor DCR or a discrete sense resistor as the sensing element.

The LTC3855 features a precision 0.6V reference and can produce output voltages up to 12.5V. A wide 4.5V to 38V input supply range encompasses most intermediate bus voltages and battery chemistries. Power loss and supply noise are minimized by operating the two controller output stages out of phase. Burst Mode operation, continuous or pulse-skipping modes are supported.

The LTC3855 can be configured for up to 12-phase operation, has DCR temperature compensation, two power good signals and two current limit set pins. The LTC3855 is available in low profile 40-pin 6mm × 6mm QFN and 38-lead exposed pad FE packages.