Pull-up resistors w/ tracks for DDR2 SDRAM.

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SUMMARY

This discussion focuses on the implementation of pull-up resistors for DDR2 SDRAM signals, specifically addressing power consumption and resistor size. It confirms that using 0402 resistors is acceptable and emphasizes the importance of impedance matching for tracks connecting resistors to VTT and signals. The conversation highlights that track length is critical, with references to PC mainboard designs illustrating the necessity of adjusting lengths to maintain signal integrity.

PREREQUISITES
  • Understanding of DDR2 SDRAM signaling
  • Knowledge of pull-up resistor configurations
  • Familiarity with impedance matching principles
  • Experience with PCB design and layout techniques
NEXT STEPS
  • Research power consumption calculations for pull-up resistors in DDR2 applications
  • Learn about impedance matching techniques for high-speed digital signals
  • Explore PCB layout best practices for DDR2 SDRAM tracks
  • Investigate the impact of trace length on signal integrity in high-frequency designs
USEFUL FOR

Electrical engineers, PCB designers, and anyone involved in the design and optimization of DDR2 SDRAM circuits.

fiedel
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When pulling up DDR2 signals with resistors, how to decide the power consumption of them, or I can just use 0402 resistors? And for the tracks connecting the resistors to the VTT (or the resistors to the signals), is there a impedance matching problem? Should them be of the same length?
 
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Take a look at a PC mainboard that uses DDR2. The pull-ups are easy to find. Just use the same size as that manufacturer uses. Yes from what I understand length is critical. Again take a look at a PC mainboard, you will see many "wiggly" lines that adjust the lengths. I don't know about impedances though.
 
I thought the wiggly lines are such signals like data and address, but not pull-ups...
 

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