Copyright © 1997 Altera Corporation 10/6/2015 P.1 Tri-State vs MUX Danny Mok Altera HK FAE...

04/21/23 P.1

Copyright © 1997 Altera Corporation

Tri-State vs MUX

Danny Mok

Altera HK FAE

([email protected])

04/21/23 P.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 ?

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External Tri-State Buffer

This Tri-State Buffer for I/O pad application

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What Altera Provide for ....

All Altera Device will provide real Tri-State Buffer at the I/O pad

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Compilation Output

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Internal Tri-State Buffer

Internal Tri-State Buffer Logic

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What Altera Provide....

Altera Max+Plus II will convert Internal Tri-State Bufferto MUX

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Can Altera support the following Design ?

04/21/23 P.9


Let us see ...

Use see, Altera can not handle this design, but the other PLD vendor X.... cando it. Altera is not Good !!!!!!!!!!

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Look at the Circuit

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What the engineer wants ?

XX ??

If there is an Internal Tri-State, what does the engineerexpect for the Output ? The circuit itself is meaningless

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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


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

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Compilation Output

No doubt about it, Altera of course this because it is meaningful design

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Anything Wrong ???

This is my existing design andwork perfectly OK, but now I wantto use Altera device to implement it.Is that OK !?!?!?

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Try it ....

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Correct Approach

WHY ?

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Closer Look

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Max+Plus II Compilation Result

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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


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

Copyright © 1997 Altera Corporation 10/6/2015 P.1 Tri-State vs MUX Danny Mok Altera HK FAE...

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