15-V, dual 3-A monolithic synchronous step-down regulator powers DDR1, DDR2 or DDR3 memory
The LTC3634 incorporates a unique constant frequency/controlled on-time, current mode architecture, which is ideal for powering DDR applications from a 12 V input supply at high switching frequencies. Its termination voltage, VTT, is set to ½ of VDDQ down to 0.6 V with accuracy of ±1.6%. The combination of a monolithic design and switching frequencies as high as 4 MHz, which enable the use of tiny, low cost capacitors and inductors, provides a very compact, high efficiency solution for DDR power applications.
Each channel of the LTC3634 uses internal switches with R DS(ON) of only 65 mOhms and 130 mOhms to deliver efficiencies as high as 95%. 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 V DDQ /2. Additional features include power good voltage monitors, input overvoltage and overtemperature protection, and short circuit protection.
The LTC3634EUFD is available in a 4 mm x 5 mm 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. Industrial grade versions, the LTC3634IUFD and LTC3634IFE, are guaranteed to operate over the -40°C to 125°C operating junction temperature range and are priced at $4.72 and $4.89 each, respectively, in 1,000-piece quantities.
More information about the LTC3634 dual-channel monolithic synchronous step-down regulator at www.linear.com/product/LTC3634.
