LTC3859

FEATURES n Dual Buck Plus Single Boost Synchronous Controllers n Outputs Remain in Regulation Through Cold Crank Down to 2.5V n Low Operating IQ: 55μA (One Channel On) n Wide Bias Input Voltage Range: 4.5V to 38V n Buck Output Voltage Range: 0.8V ≤ VOUT ≤ 24V n Boost Output Voltage Up to 60V n RSENSE or DCR Current Sensing n 100% Duty Cycle for Boost Synchronous MOSFET n Phase-Lockable Frequency (75kHz to 850kHz) n Programmable Fixed Frequency (50kHz to 900kHz) n Selectable Continuous, Pulse-Skipping or Low Ripple Burst Mode® Operation at Light Loads n Very Low Buck Dropout Operation: 99% Duty Cycle n Adjustable Output Voltage Soft-Start or Tracking n Low Shutdown IQ: 14μA n Small 38-Pin 5mm × 7mm QFN and TSSOP Packages APPLICATIONS n Automotive Always-On and Start-Stop Systems n Battery Operated Digital Devices n Distributed DC Power Systems LTC3859 Low IQ, Triple Output, Buck/Buck/Boost Synchronous Controller DESCRIPTION The LTC®3859 is a high performance triple output (buck/ buck/boost) synchronous DC/DC switching regulator controller that drives all N-channel power MOSFET stages. Constant frequency current mode architecture allows a phase-lockable switching frequency of up to 850kHz. The LTC3859 operates from a wide 4.5V to 38V input supply range. When biased from the output of the boost converter or another auxiliary supply, the LTC3859 can operate from an input supply as low as 2.5V after start-up. The 55μA no-load quiescent current extends operating runtime in battery...