DDR termination voltage

V

valtih1978

Guest
I read on termination topics and they say that having Vtt equal to the
high-to-low transition level is a bad idea (tristated buses will
noise-switch all the readers and, thus, consume unnecessary power). Yet,
JEDEC prescribes using 1.25 Vtt for DDR, based on 2.5 volt SSTL_2
signaling. Why?
 
On Sun, 09 Oct 2011 19:46:50 +0300, valtih1978 <do@not.email.me> wrote:

I read on termination topics and they say that having Vtt equal to the
high-to-low transition level is a bad idea (tristated buses will
noise-switch all the readers and, thus, consume unnecessary power). Yet,
JEDEC prescribes using 1.25 Vtt for DDR, based on 2.5 volt SSTL_2
signaling. Why?
Click to expand...
Minimum terminator power? P=V^2/R
 
On Sun, 09 Oct 2011 21:40:37 +0300, valtih1978 <do@not.email.me> wrote:

Minimum terminator power? P=V^2/R

consume more to save more!
Click to expand...
Huh? With the terminator in the middle, you save half the power (twice as
many lines, on average, 1/4 power each). The I/O obviously can't have an
issue being "hung up" in the middle.
 
http://web.cecs.pdx.edu/~greenwd/xmsnLine_notes.pdf explains the "issue":

"For three-state buses, the Théven in equivalent voltage, VThev, may be
chosen to yield a valid logic level when the bus is not being driven. It
is especi ally important in this case to choose a voltage that is not
close to the switching threshold of the receivers, lest they draw
excessive current or oscillate."
 
On Mon, 10 Oct 2011 13:12:33 +0300, valtih1978 <do@not.email.me> wrote:

http://web.cecs.pdx.edu/~greenwd/xmsnLine_notes.pdf explains the "issue":

"For three-state buses, the Théven in equivalent voltage, VThev, may be
chosen to yield a valid logic level when the bus is not being driven. It
is especi ally important in this case to choose a voltage that is not
close to the switching threshold of the receivers, lest they draw
excessive current or oscillate."
Click to expand...
....or are disabled when in the tristate condition. You know more than the
memory (bus) developers?
 
On Mon, 10 Oct 2011 13:12:33 +0300, valtih1978 <do@not.email.me> wrote:

http://web.cecs.pdx.edu/~greenwd/xmsnLine_notes.pdf explains the "issue":

"For three-state buses, the Théven in equivalent voltage, VThev, may be
chosen to yield a valid logic level when the bus is not being driven. It
is especi ally important in this case to choose a voltage that is not
close to the switching threshold of the receivers, lest they draw
excessive current or oscillate."
Click to expand...
BTW, if you know everything, why are you here?
 
Only those who do not understand experts ask questions. Those, who ask
to explain the reason behind expert decisions, should not ask the questions.
 
valtih1978 wrote:

Only those who do not understand experts ask questions. Those, who ask
to explain the reason behind expert decisions, should not ask the
questions.
Click to expand...
Have you ever gone outside and played "hide and go fuck yourself?"

The only stupid question is the one you don't ask.

And the most important thing anyone can learn in life is to question
authority.

Hope This Helps!
Rich
 
It seems that giving answers to asked questions I make people crazy.
 
On Tue, 11 Oct 2011 13:42:52 +0300, valtih1978 <do@not.email.me> wrote:

It seems that giving answers to asked questions I make people crazy.
Click to expand...
You asked the question, moron. If you think you know everything (you know
nothing), asking a question and arguing that your answer is correct (it's not)
is moronic.

Now, go away.
 
On Tue, 11 Oct 2011 11:24:04 +0300, valtih1978 <do@not.email.me> wrote:

Only those who do not understand experts ask questions.
Click to expand...
....and then argue the answer? Moron.

Those, who ask to explain the reason behind expert decisions,
should not ask the questions.
Click to expand...
What a loon.
 
valtih1978 wrote:
Only those who do not understand experts ask questions. Those, who ask
to explain the reason behind expert decisions, should not ask the questions.
Click to expand...

Plonk


--
You can't have a sense of humor, if you have no sense.
 
Those, who ask to explain the reason behind expert decisions,
should not ask the questions.

What a loon.
Click to expand...
Stupid thing? But, this is what you taught me. BTW, next time you hear
anybody asking a question, do not tell him that he knows everything.
Only morons and loons may come to such conclusion.
 
On Tue, 11 Oct 2011 21:01:58 +0300, valtih1978 <do@not.email.me> wrote:

Those, who ask to explain the reason behind expert decisions,
should not ask the questions.

What a loon.

Stupid thing?
Click to expand...
You bet! The .est.

But, this is what you taught me.
Click to expand...
Blame your parents for stupid. I wasn't there.

BTW, next time you hear anybody asking a question,
do not tell him that he knows everything.
Click to expand...
Now you're telling me what I must do? That stupid streak runs deep.

You think you do. That's the point. Why you asked the question, in the first
place, will never be known to the sane.

Only morons and loons may come to such conclusion.
Click to expand...
No, only a moron asks a question then argues the answer like they know-it-all.
Indeed, you are both.
 
On 2011-10-11, valtih1978 <do@not.email.me> wrote:
Only those who do not understand experts ask questions. Those, who ask
to explain the reason behind expert decisions, should not ask the questions.
Click to expand...
On the flipside, those who refuse to explain their conclusions are not
experts.
 
No, only a moron asks a question then argues the answer like they know-it-all.
Indeed, you are both.
Click to expand...
I pointed your attention to the "issue" that my question is about. You
started to attack me because of that. You punish people just because
they ask a question.
 
On Wed, 12 Oct 2011 13:25:21 +0300, valtih1978 <do@not.email.me>
wrote:

No, only a moron asks a question then argues the answer like they know-it-all.
Indeed, you are both.

I pointed your attention to the "issue" that my question is about. You
started to attack me because of that. You punish people just because
they ask a question.
Click to expand...
---
You're being "punished" because you're acting like an arrogant little
trolling asshole.

Or maybe it's not an act?

--
JF
 
On 12.10.2011 15:40, John Fields wrote:
You're being "punished" because you're acting like an arrogant little
trolling asshole.
Click to expand...
If you dare to ask you question in this group, you act like a trolling
arrogant assole. Thank you for reminding me this.
 
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