1. Danny Mok Altera HK FAE (dmok@altera.com)
Tri-State vs MUX
Danny Mok
Altera HK FAE
4/23/ P.1

2. 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 ?
4/23/ P.2

3. External Tri-State Buffer
This Tri-State Buffer for I/O pad application
4/23/ P.3

4. What Altera Provide for ....
All Altera Device will provide real Tri-State Buffer at the I/O pad
4/23/ P.4

5. Compilation Output
4/23/ P.5

6. Internal Tri-State Buffer
Internal Tri-State Buffer Logic
4/23/ P.6

7. What Altera Provide....
Altera Max+Plus II will convert Internal Tri-State Buffer
to MUX
4/23/ P.7

8. Can Altera support the following Design ?

9. Let us see ...
Use see, Altera can not handle this design, but the other PLD vendor X.... can
do it. Altera is not Good !!!!!!!!!!
4/23/ P.9

10. Look at the Circuit
4/23/ P.10

11. What the engineer wants ?X
If there is an Internal Tri-State, what does the engineer
expect for the Output ? The circuit itself is meaningless
4/23/ P.11

12. What is the application for
Even though some PLD vendor can provide you the Internal Tri-State Buffer
but what is the applicaton for ?
4/23/ P.12

13. 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
4/23/ P.13

14. Compilation Output
No doubt about it, Altera of course this because it is meaningful design
4/23/ P.14

15. Anything Wrong ??? This is my existing design and
work perfectly OK, but now I want
to use Altera device to implement it.
Is that OK !?!?!?
4/23/ P.15

16. Try it ....
Altera Problem ? or ???
4/23/ P.16

17. Correct Approach
WHY ?
4/23/ P.17

18. Closer Look
Tri to MUX
????
4/23/ P.18

19. Max+Plus II Compilation Result

20. 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
4/23/ P.20

21. 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
4/23/ P.21