Synchronous dual 6A step-down regulator

Analog Devices, Inc., which recently acquired Linear Technology Corporation, has announced the LTC3636 and LTC3636-1 are high efficiency, 4MHz synchronous dual output buck regulators that incorporate a unique constant frequency/controlled on-time, current mode control scheme with phase lockable switching frequency. Further, their innovative design architecture reduces conducted and radiated emissions. The devices can deliver up to 6A of continuous output current from each channel or generate a two-phase single output up to 12A. The parts accommodate output voltages as low as 0.6V from a compact 4mm x 5mm QFN package. The switching frequency is user programmable from 500kHz to 4MHz, enabling the use of tiny, low cost capacitors and inductors, and also may be synchronised to an external clock signal. The LTC3636/-1 operates from an input voltage of 3.1V to 20V, while output voltage sense ranges are 0.6V to 5V for the LTC3636 and 1.8V to 12V for the LTC3636-1, ideal for dual-cell Li-Ion applications, as well as 5V and 12V intermediate bus systems.

Each channel of the LTC3636/-1 uses internal switches with R_{DS (ON)} of only 32mΩ and 18mΩ to deliver efficiencies as high as 95 per cent. Its unique control architecture enables it to achieve duty cycles as low as 5 per cent while maintaining switching frequencies up to 2.25MHz, ideal for high step-down ratio applications such as 12V_IN to 1.8V_OUT conversions.  The two channels run 180 degrees out-of-phase, minimising the size of both input and output capacitance. The dual outputs may be combined in a two-phase configuration for up to 12A output current. Burst Mode operation is used to maximise light load efficiency, requiring 600µA at no load. For applications requiring the lowest possible noise, the LTC3636/-1 can be configured to run in forced continuous operation, reducing supply ripple and potential RF interference. Additional features include a die temperature monitor, power good voltage monitors, output voltage tracking capability, independent soft-start capability for each channel, short-circuit protection, input overvoltage and overtemperature protection.

The LTC3636 is available in a thermally enhanced, 4mm x 5mm QFN-28 package.

E- and I-grade versions are guaranteed to operate over the  ̶ 40°C to 125°C operating junction temperature, pricing starts at $4.45 each for 1,000-piece quantities of the E grade.  All versions are available from stock.