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DC/DC controller drives n-channel MOSFET

Posted: 26 May 2009 ?? ?Print Version ?Bookmark and Share

Keywords:MOSFET? n-channel? DC/DC controller?

Linear Technology Corp. has released the LTC3854, 2mm x 3mm DFN-12 packaged, wide input voltage range synchronous step-down switching DC/DC controller that drives all n-channel power MOSFET stages.

The controller's 4V to 38V input range addresses a wide variety of applications, including most intermediate bus voltages and battery chemistries. The strong on-board MOSFET gate drivers enable high power external MOSFETs to produce output currents up to 20A with output voltages ranging from 0.8V to 5.5V. This makes the LTC3854 suitable for point-of-load regulation requirements in datacom, telecom, industrial, automotive, medical and multi-function printer applications.

A constant-frequency current mode architecture provides a fixed 400kHz operating frequency. The LTC3854 features an onboard 5V regulator, eliminating the need for a separate bias voltage to power the chip. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values, including all ceramic capacitor designs. Output current sensing measures the voltage drop across the output inductor (DCR) or an optional sense resistor. Current foldback limits MOSFET heat dissipation during short-circuit and overload conditions.

In addition, the LTC3854 has adjustable soft-start to control the turn-on time and manage inrush current. Selectable continuous or discontinuous inductor current modes are available to safely power pre-biased loads. Anti-shoot-through protection prevents shoot-through current in the power MOSFETs. Operating up to 96 percent duty cycle, the LTC3854 has a very low dropout voltage for extending run times in battery-powered applications. The LTC3854 features a precision 0.8V reference with an accuracy of 1 percent over the -40C to 85C operating temperature range.

The LTC3854 is available from stock with prices starting at $1.65 in 1,000-piece quantities.

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