RE: Questions on the relationship between IBIS model & datasheet

Dear Su Ming TAI

When comparing the IBIS data to the datasheet spec

Check the section that says electrical characteristics over recommended
operating free air temperature range.

PARAMETER TEST CONDITIONS VCC MIN
Vol Iol=24 ma 3v 0.55
Voh Ioh=-24ma 3v 1.2

Now in the IBIS file in the pulldown data
[Voltage range] 3.3 3.0 3.6
500.00000mV 44.1271m 32.8243m 54.8473m
600.00000mV 52.2894m 38.6213m 65.2873m

VCC range is
[Voltage range] 3.3 3.0 3.6

and the pullup current.
1.20000V -41.5252m -29.1685m -52.8087m

[Voltage range] 3.3 3.0 3.6

The Iol in datasheet is should be the addition of groundclamp current and
pulldown current in the IBIS file.Groundclamp current is negelegible in this
device.As you can see that at VCC=3.0 volt with 0.55v volt applied minimum
current is greater than 32 ma which agrees with the datasheet that says with
3v vcc and 0.55v applied at output in low state you should get atleast 24ma.

At the pullup
1.20000V -41.5252m -29.1685m -52.8087m
[Voltage range] 3.3 3.0 3.6

pullup data is VCC relative meaning that if its min 2.2v in datasheet that
actually is max 1.2v (3-1.2v) in the pullup data in IBIS file.The Ioh in
datasheet should be the addition of pwrclamp current and pullup current in
the IBIS file.Pwrclamp current is negelegible in this device.As you can see
from the pullup data with 1.2v at output high state the current is at -29ma
which agrees with the datasheet.

Best Regards.
Moshiul Haque
Application Engineer
Standard Linear and Logic Marketing
Texas Instruments
Sherman , TX
Tel -(903) 868-7153
Fax-(903) 868-5980
e-mail- mhaque@ti.com

-----Original Message-----
From: Su Ming TAI [mailto:sm_tai@uti2000.co.jp]
Sent: Monday, December 04, 2000 8:41 PM
To: si-list@silab.eng.sun.com; ibis-users@eda.org
Subject: Questions on the relationship between IBIS model & datasheet

Dear SI & IBIS gurus,

Hi! I'm a newbie in the world of SI and I have question that some of you
may be able to explain it to me.
I have a datasheet and an IBIS model of a same device. On the datasheet
(see pg 4), the Ioh and Iol values are -24mA and 24mA respectively when Vcc
is 3V.
Now, on the IBIS model, at the pullup and pulldown section, when the
voltage is at 3V, the current are not anything near to 24mA or -24mA at all.
My question is:
1) Why is that the datasheet values do not seem to correlate with the IBIS
model?
2) How do we know that the IBIS model is correctly generated based on the
values from the datasheet?

I welcome any comments or explanations on this issue. Thanks.

Regards,
Su Ming TAI

 
Received on Thu Dec 14 09:29:57 2000