5A, 15V 2-phase synchronous boost regulator switches at 3MHz

July 08, 2014 // By Graham Prophet
LTC3124 is a dual-phase, 3 MHz, 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, minimising component size while delivering lower output ripple when compared to an equivalent single-phase device.

Internal 2.5A-per-phase capable switches together deliver 5A of switch current. These 18V switches can deliver output voltages as high as 15V from an input voltage range of 1.8V at start-up (0.5V when running) to 5.5V, making it suitable for supercapacitor-based backup power systems and Li-Ion/Polymer or multicell NiMH applications. The device delivers up to 1.5A of continuous output current at 12V from a 5V input. Synchronous rectification enables efficiencies up to 95%, while Burst Mode operation lowers quiescent current to 25 µA, providing extended battery run time. The combination of its thermally enhanced 3 x 5mm DFN-16 (or TSSOP-16) package and a constant switching frequency of up to 3 MHz, which minimises both inductor and capacitor size, provides a compact solution footprint required in handheld applications.

The LTC3124 has internal switches with an RDS(ON) of 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, minimising 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 minimise possible interference of switching noise with noise-sensitive circuitry, slightly reducing light load efficiency. Additional features include external synchronisation, output overvoltage protection, and robust short-circuit protection. The LTC3124 suits boost applications requiring outputs up to 15V where high efficiency, small solution size and high reliability are defining factors.

In 16-lead 3 x 5mm DFN and thermally-enhanced TSSOP packages, pricing starts at $3.26 (1000).

Industrial and high-temperature grade versions are available.

Linear Technology; www.linear.com/product/LTC3124