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Step-down regulator targets SDRAM controllers

Posted: 04 Jul 2011 ?? ?Print Version ?Bookmark and Share

Keywords:step-down regulator? SDRAM controller? power applications?

Linear Technology Corp. has introduced a dual-channel monolithic synchronous step-down regulator that provides power supply and bus termination rails for DDR1, DDR2 and DDR3 SDRAM controllers.

According to Linear, the LTC3634 operates from an input voltage from 3.6V to 15V that makes it ideal for dual cell Li-Ion applications, as well as 5V and 12V intermediate bus systems.

The company added that the regulator incorporates a unique constant frequency/controlled on-time, current mode architecture, suited for powering DDR applications from a 12V input supply at high switching frequencies. Its termination voltage, VTT, is set to ? of VDDQ down to 0.6V with accuracy of +1.6%.

Further, Linear said the LTC3634 has a monolithic design and switching frequencies of as high as 4MHz that enable the use of tiny, low cost capacitors and inductors. With these features, Linear said the LTC3634 provides a very compact, high efficiency solution for DDR power applications.

Each channel of the LTC3634 uses internal switches with RDS (ON) of 65mOhms and 130mOhms to deliver efficiencies as high as 95 percent. The two channels run 180 degrees out of phase, minimizing the size of both input and output capacitance. An on-chip buffer capable of driving a 10mA load provides a low noise reference output (VTTR) also at VDDQ/2.

Additional features of the LTC3634 include power good voltage monitors, input overvoltage and overtemperature protection, and short circuit protection.

Linear said the industrial grade versions, the LTC3634IUFD and LTC3634IFE, are guaranteed to operate over the -40C to 125C operating junction temperature range and are priced at $4.72 and $4.89 each, respectively, in 1,000-piece quantities.

The LTC3634EUFD is available in a 4mm x 5mm QFN-28 whereas the LTC3634EFE is available in a 28-lead TSSOP package. Pricing starts at $4.25 and $4.40 each, respectively, in 1,000-piece quantities.

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