LTC3859 Buck/Buck/Boost DC/DC Switching Controller

Analog Devices' LTC3859 is a high-performance triple output (buck/buck/boost) synchronous DC/DC switching regulator controller. This controller drives all N-channel power MOSFET stages. Constant frequency current mode architecture allows a phase-lockable switching frequency of up to 850 kHz. The LTC3859 operates from a wide 4.5 V to 38 V input supply range. When biased from the output of the boost converter or another auxiliary supply, the LTC3859 can operate from an input supply as low as 2.5 V after start-up.

The 55 μA no-load quiescent current extends operating run-time in battery powered systems. OPTI-LOOP® compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3859 features a precision 0.8 V reference for the bucks, 1.2 V reference for the boost, and a power good output indicator.

Independent TRACK/SS pins for each controller ramp the output voltages during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The PLLIN/MODE pin selects among Burst Mode® operation, pulse-skipping mode, or continuous inductor current mode at light loads.

This controller has an operating temperature range of -40°C to +125°C and +150°C and comes in QFN or TSSOP packages. The LTC3859 is perfect for distributed power supplies, battery powered, and automotive power systems.