RT9644

Preliminary RT9644/A ACPI Regulator/Controller for Dual Channel DDR Memory Systems 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 www.DataSheet4U.com V GMCH (cascode), and GMCH/CPU terminat ion VTT_GMCH/CPU. The RT9644A includes one synchronous buck controller for DDR/DDR2 VDDQ, one PWM controller for VGMCH (with external MOSFET driver), one DDR/DDR2 bus terminator VTT (equal to VDDQ/2) regulator with source and sinking ability, and two LDO controllers for VTT_GMCH/CPU and VDAC. These parts also provide a reference buffer for DDR/DDR2 input reference voltage generator. When during S0 state, the VIDPGD indicates the GMCH_CPU VTT within spec and operational. The synchronous buck DC-DC PWM is implemented by two N-MOSFETs as upper and lower MOSFETs with voltage mode control. The linear controllers are implemented with one N-MOSFET with suitable capacitance. Each output is monitored by under voltage protection (RT9644 except VGMCHH and RT9644A except VDAC). V DDQ PW M controller and DDR/DDR2 bus terminator regulator have over voltage protection. Moreover, the VDDQ PWM controller has the over current protection by external resister adjustment. Thermal shut down is integrated. All the internal...