Re: [IBIS-Users] Mixed-Signal Analog IO ?

Hello Arpad,

Sorry for my vague description. I will try to do better below.
It is clear that every buffer type have clamp tables, and that I can 
model analog IO using *-AMS langauges and External Circuit declarations. 
But since my tools fall back on s2ibis2 which conforms to IBIS v2.1 
specification which (correct me if I'm wrong), does not include these 
features, it would be an additional manual procedure to add it.
Hence my question how you did model analog IO (like for example the 
output of a bandgap reference with sink & source capability) in "the 
good old days" with only I,O,I/O,VDD,GND and NA to choose from.
If this is not possible/advisable I will of course have to take measures.

As I hope is clear from the above, I have no intention to add clamps tp 
power pins (although ESD protection calls for snapbacks), that would not 
be a good idea having multiple supplies.


Best regards,  Lars Snith


Muranyi, Arpad wrote:

> Lars,
> 
> I think you are asking the question in the right
> forum.  However, I don't understand your question.
> To include a clamp, you don't have to make it an
> input, every buffer type can have clamp tables.
> Especially if you do it using the *-AMS languages,
> you can do it any whichever way you want.  So I
> am not sure what you are asking really, or how
> to answer the question.  Please explain it better.
> 
> On the other hand, I wouldn't put clamp tables on
> power pins, it doesn't make any sense...  Clamps
> are supposed to clamp overshoot on signal pins.
> What would they do on power pins?
> 
> Arpad
> ==================================================
> 
> 
> -----Original Message-----
> From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of Lars Snith
> Sent: Monday, August 15, 2005 11:22 PM
> To: ibis-users@eda.org
> Subject: [IBIS-Users] Mixed-Signal Analog IO ?
> 
> Hello,
> 
> I hope I am adressing the right forum with this. If not, please excuse 
> my intrusion.
> 
> I have been making a number of IBIS models for microcontrollers of 
> medium complexity, successfully as it looks.
> As I will soon take on more complex products, with purely analog parts, 
> I have been considering the "correct" way of modeling a truly analog IO 
> (if at all).
> Clearly, to include the power clamps I should treat it as an input. On 
> the other hand this might not be the correct procedure, maybe it would 
> be better to treat it as a power/ground pin? It would certainly mean 
> less work. A third option is to ignore it altogether (NA).
> 
> Any comment/feedback on this issue would be most welcome.
> 
> 
> Best regards,  Lars Snith

-- 
() Join the ASCII ribbon campaign against
/\ html email and Microsoft attachments.
|------------------------------------------------------------------
|For help or to subscribe/unsubscribe, email majordomo@eda.org
|with just the appropriate command message(s) in the body:
|
|  help
|  subscribe   ibis       <optional e-mail address, if different>
|  subscribe   ibis-users <optional e-mail address, if different>
|  unsubscribe ibis       <optional e-mail address, if different>
|  unsubscribe ibis-users <optional e-mail address, if different>
|
|or email a written request to ibis-request@eda.org.
|
|IBIS reflector archives exist under:
|
|  http://www.eda.org/pub/ibis/email_archive/  Recent
|  http://www.eda.org/pub/ibis/users_archive/  Recent
|  http://www.eda.org/pub/ibis/email/          E-mail since 1993