General Description
The RT9644/A is a complete ACPI compliant power solution for DDR and DDR2 memory system with up to 4 DIMMs dual channel systems. This RT9644 includes one synchronous buck controller for DDR/DDR2 VDDQ, one DDR/DDR2 bus terminator VTT (equal to VDDQ/2) regulator with source and sinking ability, three LDO controllers for VGMCH (cascode), and GMCH/CPU termination VTT_GMCH/CPU. The RT9644A includes one synchronous buck controller for DDR/DDR2 VDDQ, one PWM controller for VGMCH (with external MOSFET driver), oneDDR/DDR2 bus terminator VTT (equal to VDDQ/2) regulator with source and sinking ability, and two LDO controllers for VTT_GMCH/CPU and VDAC.

Features
● RT9644 Includes Three LDO Controllers, One LDO Regulator and One PWM Controller
    }OneDDR/DDR2 VDDQ with Synchronous Buck PWM
    }One DDR/DDR2 Bus Terminator VTT Regulator Source/Sink 3A
    }Two Cascode LDO Controllers forGMCH Core
    }One LDO Controller forGMCH/CPU Bus Terminator VTT_GMCH/CPU
● RT9644AIncludes Two LDO Controllers, One LDO Regulator and Two PWM Controllers
    }OneDDR/DDR2 VDDQ with Synchronous Buck PWM
    }One VGMCH with External Richtek MOSFET Driver
    }One DDR/DDR2 Bus Terminator VTT Regulator Source/Sink 3A
    }One LDO Controller for VDAC
    }One LDO Controller for GMCH/CPU Bus
    Terminator VTT_GMCH/CPU
● Operating with 5V and 12V Supply Voltage
● ACPI Compliant Sleep Mode Control
● DriveAll Low Cost N-MOSFETs
● Voltage Mode PWM Control
    }250kHz Fixed Frequency Oscillator (RT9644A: Two PWM controllers with phase shift 90o)
    }Simple Voltage Mode Loop Control
    }Fast Transient Response
    }Over Current Protection
● Fully Adjustable Output Voltage Down to Compatible with DDR2
● Integrated DDR/DDR2 Reference Buffer
● Integrated VIDPGD to Indicated VTT_GMCH/CPU Operational
● All Regulator Outputs Monitored by Under Voltage Protection
● DDR/DDR2 VDDQ and Bus Terminator VTT Also Integrated Over Voltage Protection
● Integrated Thermal Shut Down
● RoHS Compliant and 100% Lead (Pb)-Free

Applications
● Motherboard, Desktop Servers : Single/Dual channel DDR/DDR2ACPI compliant
● Graphic Card : GPU and memory supply
● IA Equipments
● Telecomm Equipments
● DSP, ASIC or embedded processor and IO supplies
● High Power DC-DC Regulators