The LTC1435 is a synchronous step-down switching regulator controller that drives external N-channel power MOSFETs using a fixed frequency architecture. Burst Mode™operation provides high efficiency at low load currents. A maximum duty cycle limit of 99% provides low dropout operation which extends operating time in battery-operated systems.The operating frequency is set by an external capacitor allowing maximum flexibility in optimizing efficiency. A secondary winding feedback control pin, SFB, guarantees regulation regardless of load on the main output by forcing continuous operation. Burst Mode operation is inhibited when the SFB pin is pulled low which reduces noise and RF interference.Soft start is provided by an external capacitor which can be used to properly sequence supplies. The operating current level is user-programmable via an external current sense resistor. Wide input supply range allows operation from 3.5V to 30V (36V maximum).For a guaranteed and test minimum on-time refer to the LTC1435A, the "A" version of the LTC1435. The minimum on-time of the LTC1435A is guaranteed to be ≤300ns. The only difference between these two parts is this guaranteed minimum on-time. Pricing is the same.ApplicationsNotebook and Palmtop Computers, PDAsCellular Telephones and Wireless ModemsPortable InstrumentsBattery-Operated DevicesDC Power Distribution Systems