DDR2 w/o Termination

Charles Gervasi

I have a single DDR2 chip located next to a '6746. I put all the suggested termination from the datasheet on my schematic. Now that I'm laying it out, I'm thinking the signal paths would be significantly shorter if I just omitted the resistors. If I keep the signals under an inch and always referenced to ground with 50 ohm impedance, am I safe to omit the termination?

over 14 years ago

0 Brad Griffis over 14 years ago

TI__Guru*** 125430 points

According to the data sheet:

"No terminations of any kind are required in order to meet signal integrity and overshoot requirements.
Serial terminators are permitted, if desired, to reduce EMI risk; however, serial terminations are the only
type permitted."

0 Charles Gervasi over 14 years ago in reply to Brad Griffis

Expert 2270 points

The proof of the pudding will be in the eating. :)

I have read the datasheet. I was hoping to hear from someone how it worked for them w/o termination. I'm going to go for it and try to remember to come back here and let you know how it went.

0 jc-ti over 14 years ago in reply to Charles Gervasi

TI__Mastermind 27585 points

I've seen many customer designs that do not use terminators and they all worked fine. The only concern might be EMI, if that is a major concern in your design.

Jeff

0 Thomas Wappler over 14 years ago in reply to Charles Gervasi

Intellectual 395 points

Hi Charles,

did you get results from your test without termination resistors? I'm currently doing a design and also considering to left them out.

Thanks,

Thomas.

Processors

Processors forum

DDR2 w/o Termination