Linear Technology LTC3852 step-down DC/DC controller

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Linear Technology has released the LTC3852, a low/wide input voltage (2.7 to 5.5 or 4-38) synchronous step-down DC/DC controller.

The device’s onboard charge pump provides 5 V bias to drive low R_DS(ON) and standard logic-level power MOSFETs from a 3.3 V nominal supply.

Since the LTC3852’s internal charge pump and DC/DC controller are independent, the charge pump output can provide 5 V to power the internal gate drivers, and the DC/DC converter power stage can draw power from another source (up to 38 V maximum).

Output currents up to 25 A can be supplied over an output voltage range from 0.8 to 99% of V_IN (2.7-5.5 V), making the device suitable for 3.3 V-powered point-of-load applications.

A constant-frequency current-mode architecture allows a selectable fixed or phase-lockable frequency from 250 to 750 kHz. Selectable Burst Mode operation, pulse skip or forced continuous mode is user controlled to optimise light load efficiency. 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 for highest efficiency or by using an optional sense resistor in series with the inductor for highest accuracy. Current foldback limits MOSFET heat dissipation during short-circuit and overload conditions.

The controller has adjustable soft-start or tracking to control the turn-on characteristics of the supply, and features an 0.8 V reference with an accuracy of ±1.25% over a -40 to 125°C operating temperature range.