Accepting inputs above, below, or equal to the output, the LTC3530 is a synchronous buck-boost converter that delivers up to 600 mA of output current to a regulated output voltage. The device's input range of 1.8 V to 5.5 V and output range of 1.8 V to 5.25 V is compatible with single-cell Li-ion or dual-cell alkaline/NiCad/NiMH applications. The LTC3530's topology provides a continuous transfer mode through all operating modes, making it well-suited for applications that must maintain a constant output voltage even as the battery voltage declines below the output. In many cases, this can increase battery run time by up to 20%. The chip's constant switching frequency provides low noise and is user programmable from 300 kHz to 2 MHz, allowing optimization between efficiency and solution size. The combination of compact externals and a 3- by 3-mm DFN or MSOP-10 package provide a small solution footprint.
The LTC3530 includes two N-channel MOSFETs and two P-channel MOSFETs (0.21 Ω and 0.24 Ω, respectively) to deliver efficiencies of up to 96%. Programmable Burst Mode operation allows the user to adjust the load current at which Burst Mode initiates. Burst Mode operation requires only 40 µA of quiescent current while shutdown current is less than 1 µA, further extending battery runtime. Other features include soft start, current limiting, thermal shutdown and output disconnect.
The LTC3530EDD is available from stock in a 10-lead DFN package, and the LTC3530EMS is available in a 10-lead MSOP package. Both versions cost $2.75 each for 1,000-piece quantities.