20V, 4 MHz, synchronous 2x 6A step-down regulator in 20 sq mm

The devices can deliver up to 6A of continuous output current from each channel or generate a 2-phase single output up to 12A. The parts accommodate output voltages as low as 0.6V from a 4 x 5 mm QFN package. The switching frequency is user programmable from 500 kHz to 4 MHz, enabling the use of tiny, low cost capacitors and inductors, and also may be synchronized to an external clock signal. The LTC3636/-1 both operate 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, 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 32 mΩ and 18 mΩ to deliver efficiencies as high as 95%. Its control architecture enables it to achieve duty cycles as low as 5% while maintaining switching frequencies up to 2.25 MHz, for high step-down ratio applications such as 12 VIN to 1.8 VOUT conversions. The two channels run 180 degrees out-of-phase, minimizing the size of both input and output capacitance. The dual outputs may be combined in a 2-phase configuration for up to 12A output current. Burst Mode operation is used to maximize light load efficiency, requiring 600 µA at no load.

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