RE: [IBIS-Users] Warning - "Typical value never becomes zero"

From: Tom Dagostino <tom_at_.....> Date: Mon Jul 11 2005 - 10:20:52 PDT · This archive was generated by hypermail 2.1.8 : Mon Jul 11 2005 - 10:22:12 PDT

Before you change your model you need to understand what is causing the
currents that you see.  Is there some kind of weak pulldown device
associated with his input?

If you just change one entry in your IV tables you are likely to cause other
problems.  You have not shown us any other data from the tables.  If you
just change the 0.00V current value you will likely get a non-monotonic
error.

Warnings are OK in IBIS models if you have done the engineering to know that
the cause of the warning is really the characteristic of the device.

Tom Dagostino
Teraspeed(R) Labs
13610 SW Harness Lane
Beaverton, OR 97008
503-430-1065
tom@teraspeed.com
www.teraspeed.com

Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
401-284-1827

-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org]On
Behalf Of nilimp.vipul@wipro.com
Sent: Monday, July 11, 2005 5:56 AM
To: Vivek.Kumar.Sundriyal@nsc.com; ibis-users@eda.org
Subject: RE: [IBIS-Users] Warning - "Typical value never becomes zero"

Hi Vivek,

I have the following opinion about your problem.

1) For 0.0V as input your typical and maximum current values are
significantly higher than they should be. The minimum current value is
tolerable. They should be in micro-amps(i.e extremely low...very close
to 0.0 A). Hence the errors.

2)You can remove the "Model MODEL1: POWER Clamp : Minimum value never
becomes zero WARNING " by simply changing the
Minimum current to 0.3000uA from 72.3000uA. Since the current is already
in micro-Amperes this change will be quite insignifucant.

3)However you cannot do this to your typ and max curent readings, since
such a change will be considered as a significant change. I suggest you
go back to your netlist design,source files and check the Power Clamp
part once again.

Hope this helps.

Regards,
Nilimp Bhatt

-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On
Behalf Of Vivek Kumar Sundriyal
Sent: Monday, July 11, 2005 5:40 PM
To: ibis-users@eda.org
Subject: [IBIS-Users] Warning - "Typical value never becomes zero"

Hi ,

I have developed the IBIS model using s2ibis3 and I am using IBIS
version 3.2

When I compile the .ibs file, I get the following warning  :

WARNING -
    Model MODEL1: POWER Clamp : Typical value never becomes zero WARNING
-
    Model MODEL1: POWER Clamp : Minimum value never becomes zero WARNING
-
    Model MODEL1: POWER Clamp : Maximum value never becomes zero

On looking at the Power clamp data, the current values that I get at
0.0V are :
0.3193mA      72.3000uA      0.6643mA
for typ,min and max respectively.

Can anyone elaborate on this warning ?

And how serious is this ?

Cheers ,

Vivek

|------------------------------------------------------------------
|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

Confidentiality Notice

The information contained in this electronic message and any attachments to
this message are intended
for the exclusive use of the addressee(s) and may contain confidential or
privileged information. If
you are not the intended recipient, please notify the sender at Wipro or
Mailadmin@wipro.com immediately
and destroy all copies of this message and any 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