Linear Technology Corporation introduced the LTC3124, 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 external component size while delivering lower output ripple versus an equivalent single-phase device.
This architecture enhances output drive capability with its internal 2.5A per phase capable switches together delivering 5A of switch current.
With an input voltage range of 1.8V at start-up (0.5V when running) to 5.5V, these 18V switches can deliver output voltages as high as 15V, making it ideal for supercapacitor-based backup power systems and Li-Ion/Polymer or multicell NiMH applications. The buck 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 only 25µA, providing extended battery run time. The device also has internal switches with an RDS(ON) of only 130mOhm (N-channel) and 200mOhm (P-channel) that help deliver efficiencies as high as 95%. The added benefit from all of this in the minimizing of thermal concerns.
The combination of its thermally enhanced 3mm x 5mm DFN-16 (or TSSOP-16) package and a constant switching frequency of up to 3MHz, which minimizes both inductor and capacitor size, provides a compact solution footprint required in handheld applications.
The IC’s output disconnect feature eliminates body diode conduction of the internal P-channel MOSFET rectifiers. This feature allows for VOUT to discharge to 0V during shutdown, and draw no current from the input source. Inrush current will also be limited at turn-on, minimizing surge currents seen by the input supply. Note that to obtain the advantages of output disconnect, there must not be an external Schottky diode connected between SWA, SWB and VOUT. The output disconnect feature also allows VOUT to be pulled high, without backfeeding the power source connected to VIN.
The IC 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 buck 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.
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