The LTC3569 three-channel, high-efficiency 3-MHz synchronous buck regulator from Linear Technology Corp. delivers up to 1.2 A of continuous output current from one channel and 600 mA from each of the two other channels. The device uses a constant-frequency, current-mode architecture and operates from an input voltage of 2.5 to 5.5 V, making it well-suited for single-cell Li-ion polymer of multicell alkaline, NiCad, or NiMH applications.

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Users can independently program each of the three output voltages by lowering the feedback voltage of each channel from 800 to 425 mV (in 25-mV increments). This is performed by toggling the EN pin. Additionally, both 600-mA regulators can act as slave power stages to each other or to the 1.2-A channel to support higher currents, increasing design flexibility. Frequency can be programmed between 1 and 3 MHz or set at 2.5 MHz. This allows the designer to optimize efficiency while avoiding critical noise-sensitive frequencies.

The LTC3569’s 3- by 3-mm QFN-20 (or TSSOP-16E package) and its high switching frequency keep external inductors and capacitors small, creating a very compact, thermally efficient footprint. The device’s internal synchronous switches offer efficiencies as high as 95%, while Burst Mode operation holds quiescent current to only 100 μA (all three channels) in no-load conditions. To achieve the lowest possible noise, the regulator can run in a pulse-skipping mode that minimizes output ripple.

The LTC3569EUD comes in the QFN-20 package and the LTC3569EFE comes in a 16-lead thermally enhanced TSSOP package. Prices start at $3.10 and $3.20 each, respectively, in lots of 1000. Industrial-grade versions, the LTC3569IUD and LTC3569IFE, are tested and guaranteed to operate at junction temperatures from –40°C to 85°C. They cost $3.65 and $3.75 each, respectively, in 1000-piece quantities. All versions are available from stock.

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