Post on 12-Jan-2016
04/21/23 P.1
Copyright © 1997 Altera Corporation
Tri-State vs MUX
Danny Mok
Altera HK FAE
(dmok@altera.com)
04/21/23 P.2
Copyright © 1997 Altera Corporation
Tri-State Buffer
There are two application area for the Tri-State Buffer– Internal Tri-State Buffer Logic
• need a Tri-State Buffer within Device– External Tri-State Buffer Logic
• need a Tri-State Buffer at the I/O pin
What Altera can provide– Altera will implement Internal Tri-State Buffer with MUX– All the I/O pad can provide a real Tri-State Buffer
But some other PLD vendor can provide – Internal Tri-State Buffer
Is that any design limitation if use Altera Device ?
04/21/23 P.3
Copyright © 1997 Altera Corporation
External Tri-State Buffer
This Tri-State Buffer for I/O pad application
04/21/23 P.4
Copyright © 1997 Altera Corporation
What Altera Provide for ....
All Altera Device will provide real Tri-State Buffer at the I/O pad
04/21/23 P.5
Copyright © 1997 Altera Corporation
Compilation Output
04/21/23 P.6
Copyright © 1997 Altera Corporation
Internal Tri-State Buffer
Internal Tri-State Buffer Logic
04/21/23 P.7
Copyright © 1997 Altera Corporation
What Altera Provide....
Altera Max+Plus II will convert Internal Tri-State Bufferto MUX
04/21/23 P.8
Copyright © 1997 Altera Corporation
Can Altera support the following Design ?
04/21/23 P.9
Copyright © 1997 Altera Corporation
Let us see ...
Use see, Altera can not handle this design, but the other PLD vendor X.... cando it. Altera is not Good !!!!!!!!!!
04/21/23 P.10
Copyright © 1997 Altera Corporation
Look at the Circuit
04/21/23 P.11
Copyright © 1997 Altera Corporation
What the engineer wants ?
XX ??
If there is an Internal Tri-State, what does the engineerexpect for the Output ? The circuit itself is meaningless
04/21/23 P.12
Copyright © 1997 Altera Corporation
What is the application for
Even though some PLD vendor can provide you the Internal Tri-State Buffer– but what is the applicaton for ?
04/21/23 P.13
Copyright © 1997 Altera Corporation
Can Altera support this ?
Before consider whether Altera support it or not ? First ask is this a meaningful circuit
Yes, this is meaningful circuit
Altera support all kind of meaningful circuit
04/21/23 P.14
Copyright © 1997 Altera Corporation
Compilation Output
No doubt about it, Altera of course this because it is meaningful design
04/21/23 P.15
Copyright © 1997 Altera Corporation
Anything Wrong ???
This is my existing design andwork perfectly OK, but now I wantto use Altera device to implement it.Is that OK !?!?!?
04/21/23 P.16
Copyright © 1997 Altera Corporation
Try it ....
04/21/23 P.17
Copyright © 1997 Altera Corporation
Correct Approach
WHY ?
04/21/23 P.18
Copyright © 1997 Altera Corporation
Closer Look
04/21/23 P.19
Copyright © 1997 Altera Corporation
Max+Plus II Compilation Result
04/21/23 P.20
Copyright © 1997 Altera Corporation
Conclusion
Altera provide complete solution for Tri-State Buffer Design– Internal Tri-State Buffer
• Altera Max+Plus II will convert Internal Tri-State Buffer to MUX
• MUX solution provide more advantage then real Tri-State Buffer
– no signal contention
– smaller in die size -> low device cost
– External Tri-State Buffer
• All Altera Device I/O pad provide a real Tri-State Buffer
04/21/23 P.21
Copyright © 1997 Altera Corporation
A lot of Design need a real Tri-State Buffer at I/O – almost all the PLD vendor provide this solution, of course
ALTERA does
Some PLD vendor emphasize support Internal Tri-State Buffer– there is no meaningful application for this