1-A synchronous buck-boost DC/DC converter delivers extended battery run time for Li-Ion and alkaline-powered devices

August 04, 2011 // By Paul Buckley
Linear Technology has introduced a synchronous buck-boost converter that delivers up to 1 A of output current from a Li-Ion/Polymer source or 300 mA from dual cell alkaline/NiCd/NiMH sources. The LTC3536’s 1.8 V to 5.5 V input and output voltage range achieves a ±1% accurate output with inputs above, below or equal to the regulated output.

The latest generation single inductor buck-boost pulse width modulation (PWM) topology incorporated in the LTC3536 provides a continuous transition through all of the operating modes, making it ideal for noise-sensitive 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 25% versus a buck regulator.

The LTC3536’s switching frequency is user programmable from 300 kHz to 2 MHz and can be synchronized to a system clock, optimizing the trade-off between efficiency and external component size. The combination of 1% output voltage accuracy, low noise, tiny externals and a 3 mm x 3 mm DFN package provides a small solution footprint, typically required in many handheld RF and precision measurement applications.

The LTC3536 includes two N-channel MOSFETs and two P-channel MOSFETs (R DS(ON) of 0.06 Ohm and 0.08 Ohm, respectively) to deliver efficiencies up to 95%. Burst Mode operation is user programmed to improve efficiency at light loads and requires only 28 uA of quiescent current. Shutdown current is less than 1 uA, further extending battery run time. Other features include soft-start, short circuit protection, current limiting and thermal shutdown.

LTC3536 is available from stock in thermally enhanced 10-lead 3mm x 3mm DFN and 12-lead MSOP packages in both E and I grades. Pricing starts at $2.75 each in 1,000-piece quantities.

More information about the LTC3536 synchronous buck-boost converter at www.linear.com/product/LTC3536.