Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
13 years ago

ddr2 io standard

1. Are all the pins of ddr2 SSTL-18 or just DQ,DQS pins?

If I config the DQ and DQS pins as SSTL-18 and others 2.5V.Does it work?

2. SSTL-18 Class I and SSTL-18 Class II are both ok,right?:)

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    13 years ago

    All DDR2 control lines (address,# RAS,# CAS,# WE etc.) are specified to use a voltage referenced IO standard with termination resistors. It's a different question, if it's possible to drive the pins e.g. with 1.8V CMOS, but clearly not 2.5V. In any case, it would be outside specified operation.

    Using single or dual terminated SSTL is matter of signal quality and connection length. Class I is mostly used for FPGA DDR interfaces.