[SI-LIST] Driving current
- From: rajat.chauhan@xxxxxx
- To: ched_chang@xxxxxxxxxxx
- Date: Tue, 23 Apr 2002 21:44:03 +0530
!
! Dear all,
! I have a question regarding the driving currents of IC.
! Say, I get the following information from the Data Sheet:
!
! Iol=4mA at Vol=0.4V
! Ioh=-4mA at Voh=2.4V
Better read it: Vol(max)=0.4V at Iol=4mA
Voh(min)=2.4V at Ioh=-4mA
So if you keep more Iol and Ioh then specified, you make Vol lower and
Voh higher for 4mA sourcing/sinking currents. By this vendors are actualy
providing with extra noise margin then what they specify.
!
! How can I extract the same infomation from the IBIS?
You can plot the I/V characteristics curves for sourcing and sinking.
Infact your vendor must have provided you with these curves.
!
! I presume that the Ioh and Iol will be extracted from the Pullup and
! Pulldown VI tables. But I discover that the Pullup and Pulldown
currents in
! the IBIS are always much larger as compared to currents given in Data
Sheet.
! Can someone please explain this to me?
As these are guaranteed minimum current rating for given Vol/Voh, so
drivers are designed to fullfill these specs in the worst operating
conditions(PVT).Infact even in the worst conditions these currents are
kept slightly higher (say 6 or 8mA) to be on safer side. But when the
same driver is tested for best or even typical conditions, gives much
higher currents, 30,40mA or more....
!
! Thank you very much in advance.
! --
! Regards,
! Chai
!
____________________________________________
RAJAT CHAUHAN
STMicroelectronics
NOIDA
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