Step-down convertor is small and cool

Dual-output synchronous step-down switching regulator controller drives all N-channel power MOSFET stages with coincident or ratiometric tracking.

Available now from Linear Technology, the LTC3850 is a 95%-efficient dual-output synchronous step-down switching regulator controller that drives all N-channel power MOSFET stages with coincident or ratiometric tracking.

The 4 to 24V input range encompasses a wide variety of applications including most intermediate bus voltages and battery chemistries.

The strong onboard driver allows the use of high power external MOSFETs to produce output currents up to 20A with output voltages ranging from 0.8 to 5.5V.

Applications include notebook and tablet PCs, portable instruments, datacomms, telecomms, set-top boxes, basestations and multifunction printers where a step-down DC/DC convertor must deliver high power with low heat dissipation in a small solution size.

A constant-frequency current-mode architecture allows a selectable fixed or phase-lockable (PLL) frequency from 250 to 780kHz.

Power loss and supply noise are minimised by operating both stages 180 degrees out-of-phase.

Opti-Loop compensation allows the transient response to be optimised over a wide range of output capacitance and ESR values, including all ceramic input and output capacitors.

Output current sensing is accomplished by measuring the voltage drop across the output inductor or by using an optional sense resistor.

Current foldback limits MOSFET heat dissipation during short-circuit conditions.

In addition, the LTC3850 has adjustable soft-start to control the turn-on time.

Selectable Burst Mode operation, pulse skipping mode or continuous inductor current mode is user controlled to optimise light load efficiency against output ripple.

The LTC3850 features a precision 0.8V reference with an accuracy of +/-1% over a -40 to +85C operating temperature range.

With up to 97% duty cycle, the LTC3850 has a very low dropout voltage, a useful feature for extending run times in battery powered applications.

The LTC3850 is offered in a thermally enhanced 4 x 4mm QFN-28 and SSOP-28 packages.

Pricing for 1000-piece quantities begins at US $2.40 each.

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