General Description
The MAX8550/MAX8551 integrate a synchronous-buck PWM controller to generate VDDQ, a sourcing and sinking LDO linear regulator to generate VTT, and a 10mA reference output buffer to generate VTTR. The buck controller drives two external N-channel MOSFETs to generate output voltages down to 0.7V from a 2V to 28V input with output currents up to 15A. The LDO can sink or source up to 1.5A continuous and 3A peak current. Both the LDO output and the 10mA reference buffer output can be made to track the REFIN voltage. These features make the MAX8550/MAX8551 ideally suited for DDR memory applications in desktops, notebooks, and graphic cards.

FEATUREs
Buck Controller
♦ Quick-PWM with 100ns Load-Step Response
♦ Up to 95% Efficiency
♦ 2V to 28V Input Voltage Range
♦ 1.8V/2.5V Fixed or 0.7V to 5.5V Adjustable Output
♦ Up to 600kHz Selectable Switching Frequency
♦ Programmable Current Limit with Foldback Capability
♦ 1.7ms Digital Soft-Start and Independent Shutdown
♦ Overvoltage/Undervoltage-Protection Option
♦ Power-Good Window Comparator

LDO Section
♦ Fully Integrated VTT and VTTR Capability
♦ VTT has ±3A Sourcing/Sinking Capability
♦ VTT and VTTR Outputs Track VREFIN / 2
♦ All-Ceramic Output-Capacitor Designs
♦ 1.0V to 2.8V Input Voltage Range
♦ Power-Good Window Comparator

APPLICATIONs
    DDR I and DDR II Memory Power Supplies
    Desktop Computers
    Notebooks and Desknotes
    Graphic Cards
    Game Consoles
    RAID
    Networking