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Two-Phase Synchronous Boost Regulator Offers 95% Efficiency

Aug. 7, 2014
2-Phase Synchronous Boost Regulator Offers 95% Efficiency

The LTC3124 from Linear Technology Corporation is a dual-phase, 3MHz, current-mode, synchronous boost DC/DC converter with output disconnect and inrush current limiting. Dual-phase operation significantly reduces peak inductor and capacitor ripple currents, minimizing component size while delivering lower output ripple versus an equivalent single-phase device. Its internal 2.5 A per phase capable switches together deliver 5 A of switch current. These 18 V switches can deliver output voltages as high as 15 V from an input voltage range of 1.8 V at start-up (0.5 V when running) to 5.5 V, making it ideal for supercapacitor-based backup power systems and Li-Ion/Polymer or multi-cell NiMH applications. The LTC3124 delivers up to 1.5 A of continuous output current at 12 V from a 5 V input. Synchronous rectification enables efficiencies up to 95%, while Burst Mode® operation lowers quiescent current to only 25 µA, providing extended battery run time. The combination of its thermally enhanced 3 mm x 5 mm DFN-16 (or TSSOP-16) package and a constant switching frequency of up to 3 MHz, which minimizes both inductor and capacitor size, provides a compact solution footprint required in handheld applications.

The LTC3124 has internal switches with an RDS(ON) of only 130 mΩ (N-channel) and 200 mΩ (P-channel) to deliver efficiencies as high as 95%. The output disconnect feature allows the output to be completely discharged in shutdown. It also limits the inrush of current during start-up, minimizing surge currents seen by the input supply. The LTC3124 will also regulate the output voltage when the input voltage exceeds the output voltage, enabling compatibility with any battery chemistry. For applications demanding the lowest possible noise operation, the LTC3124 can be set via an external pin to operate in a continuous frequency mode. This version runs in continuous mode at all current levels to minimize possible interference of switching noise with noise-sensitive circuitry, slightly reducing light load efficiency. Additional features include external synchronization, output overvoltage protection, and robust short-circuit protection. The LTC3124 delivers an ideal solution for boost applications requiring outputs up to 15 V where high efficiency, small solution size and high reliability are defining factors.

The LTC3124EDHC and LTC3124EFE are both available from stock in 16-lead 3mm x 5mm DFN and thermally enhanced TSSOP packages, respectively. 1,000-piece pricing starts at $3.26 each. Industrial grade versions, the LTC3124IDHC and LTC3124IFE, are guaranteed to operate over the -40 °C to 125 °C operating junction temperature range and a high temperature grade version, the LTC3124HFE is guaranteed to operate over -40 °C to 150 °C. All versions are available from stock. For more information, visit www.linear.com/product/LTC3124.


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