The LTC1143 series is a dual step-down switching regulator controller featuring automatic Burst Mode™operation to maintain high efficiencies at low output currents. This device is composed of two separate regulator blocks, each driving an external power MOSFET at switching frequencies up to 400kHz using a constant off-time current mode architecture. Both fixed and adjustable voltages are available.The operating current level for both regulators is user-programmable via an external current sense resistor. Wide input supply range allows operation from 4V to 14V (16V maximum). The LTC1143L and LTC1143L-ADJ extend operation to VIN= 3.5V. 100% duty cycle provides low dropout regulation limited only by the RDS(ON)of the external MOSFET and resistance of the inductor and current sense resistor.The LTC1143 series is ideal for applications requiring dual output voltages with high conversion efficiencies over a wide load current range in a small amount of board space.ApplicationsPersonal Digital AssistantsNotebook and Palmtop ComputersBattery-Operated Digital DevicesPortable InstrumentsDC Power Distribution Systems