DDR system consideration

DDR SYSTEM DESIGN CONSIDERATIONDDR System Design Considerations

Integrated Technology Group Micron

1

DDR Overview

2

SSTL2 Signal Levels
Driver

Receiver

December, 00

3

SSTL2 Double Ended Termination
VTTTermination Island VTT/VREF Generator

SSTL_2

Address/Cmnd Chip Selects

PC266 SDRAM Reg. DIMM

Chipset
“North Bridge”
SSTL_2

PC266 SDRAM Reg. DIMM

Address / Command

VTT Termination Island

Data/Strobe/Mask

December, 00

4

SSTL2 Single Ended Termination
VTT/VREF Generator

SSTL_2

Address/Cmnd Chip Selects

Chipset
“North Bridge”
SSTL_2

PC266 SDRAM Reg. DIMM

PC266 SDRAM Reg. DIMM

Address/Command

VTT Termination Island

Data/Strobe/Mask

December, 00

5

Use Single Parallel Termination Resistor With Series Resistor
m Lower system cost m Easier motherboard route m Improved bandwidth m Lower skew due t