Synchronous buck-boost converter boasts low quiescent current



The LTC3129 synchronous buck-boost converter from Linear Technology delivers up to 200mA of continuous output current from a wide variety of input sources including single or multiple-cell batteries as well as solar panels and supercaps. Its 2.42V to 15V input range and 1.4V to 15.75V output range provide a regulated output with inputs above, below or equal to the output. The low noise buck-boost topology incorporated in the LTC3129 provides a continuous transition through all of the operating modes, making it ideal for applications that must maintain a constant output voltage, even as the input source voltage transitions through the output voltage. It also includes programmable maximum power point control (MPPC) capability, ensuring maximum power extraction from nonideal power sources such as photovoltaic cells. Quiescent current of only 1.3μA makes the LTC3129 well suited for always on and energy harvesting applications in which extended battery run time is of primary importance. The LTC3129's constant 1MHz switching frequency ensures low noise and high efficiency, while minimizing the size of the external components. The combination of tiny externals and a 3mm x 3mm QFN or MSOP-16E package provides a very small solution footprint. The LTC3129 includes four internal low RDSON N-channel MOSFETs to deliver efficiencies of up to 95%. User selectable Burst Mode® operation lowers quiescent current to only 1.3μA improving light load efficiency and extending battery run time. For noise sensitive applications, Burst Mode operation can be disabled, offering low noise continuous switching. Other features include a power good indicator, current-mode control, internal compensation thermal shutdown and output disconnect. The LTC3129-1 shares all of the features of the LTC3129, but offers eight fixed output voltages from 2.5V to 15V. These outputs are user-programmable and eliminate the resistor divider required on the adjustable version. Both the LTC3129EUD and LTC3129EUD-1 are available in a 16-lead 3mm x 3mm QFN package, whereas the LTC3129EMSE and LTC3129EMSE-1 are offered in a thermally enhanced 16-lead MSOP package. Pricing starts at $2.95 each for both versions. Industrial grade versions, the LTC3129IUD, LTC3129IUD-1, LTC3129IMSE and LTC3129IMSE-1, are guaranteed to operate over the -40°C to 125°C operating junction temperature range and are priced at $3.25 each. All pricing is based on 1,000-piece quantities and all versions are available from stock. Linear Technology