Step down regulator powers ddr1, ddr2 and ddr3 memory
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Linear Technology's LTC3634 is a dual channel monolithic synchronous step down regulator, which provides power supply and bus termination rails for ddr1, ddr2 and ddr3 SDRAM controllers.
The device operates from an input voltage from 3.6 to 15V and is targeted at dual cell Li-Ion applications as well as 5 and 12V intermediate bus systems. It incorporates a constant frequency/controlled on time, current mode architecture, which is suitable for powering ddr applications from a 12V input supply at high switching frequencies. Its termination voltage is set to ½ of VDDQ down to 0.6V with an accuracy rated at ±1.6%.
Each channel uses internal switches with Rds(on) of 65 and 130Mohms to deliver efficiencies up to 95%. The two channels run 180° out of phase, minimising the size of both input and output capacitance. An on-chip buffer capable of driving a 10mA load is optimised to provide a low noise reference output also at VDDQ/2. Additional features include power good voltage monitors, input overvoltage and overtemperature protection, as well as short circuit protection.
