Low Input Voltage, Synchronous Step-Down DC/DC Controller

The LTC3852 is a constant frequency, current mode step-down DC/DC controller which can be powered by an on-board charge pump. Input supplies as low as 2.7V, when doubled by the charge pump, provide 5V to the LTC3852’s control logic and gate drives, supporting a wide selection of logic-level N-channel power MOSFETs.

The constant-frequency current mode architecture allows for a phase-lockable fixed frequency of up to 750kHz. The RUN pin provides a precision enable threshold while the TRACK/SS pin combines tracking and adjustable soft-start features.

The MODE/PLLIN pin selects among Burst Mode® operation, pulse-skipping mode, and continuous current mode. Current foldback limits MOSFET power dissipation during short-circuit conditions. Reverse current and current foldback functions are disabled during soft-start. A power good output pin indicates when the output is within ±10% of its designed set point.

Applications

* General Purpose 3.3V Systems

* Lithium-Ion Powered Devices

* Distributed DC Power Systems

* Charge Pump Input Range: 2.7V to 5.5V

* Controller Input Range: 4V to 38V

* Integrated Charge Pump Provides 5V Gate Drive to Logic Level MOSFETs

* RSENSE or DCR Current Sensing

* ±1.25% Output Voltage Accuracy Over Temperature

* Phase-Lockable Fixed Frequency: 250kHz to 750kHz

* Power Good Output Voltage Monitor

* Adjustable Soft-Start Voltage Ramping

* Current Foldback Disabled During Start-Up

* No Reverse Current During Soft-Start

* Selectable Constant Frequency, Pulse-Skipping, or Burst Mode Operation

* Output Overvoltage Protection

* Very Low Dropout Operation: 99% Duty Cycle

* Available in a 24-Lead (3mm × 5mm) QFN Package