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Visitor tvgod2000
Visitor
471 Views
Registered: ‎07-27-2018

I want to know the delay between I and O in any BUFFER.

Hi, I'm using Spartan6 SP605 evaluation board.

I refer to "ds162_DC and Switching Characters datasheet" but only found the BUFGMUX delay from I to O.

If I want to know the delay from I to O in another buffer(OBUF, IBUF), what should I refer to? Or can you let me know?

 

And the additional question, is it possible to function as a buffer that only BUFG, OBUF, IBUF?

If there is anything else, please reply. Thank you.

 

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6 Replies
Scholar watari
Scholar
462 Views
Registered: ‎06-16-2013

Re: I want to know the delay between I and O in any BUFFER.

Hi @tvgod2000

 

> If I want to know the delay from I to O in another buffer(OBUF, IBUF), what should I refer to? Or can you let me know?

 

Would you do STA with what you want to use ?

 

> And the additional question, is it possible to function as a buffer that only BUFG, OBUF, IBUF?

 

It depends on IO buffer type (ex. LVTTL, LVDS and SSTL-18...).

 

Best regards,

Visitor tvgod2000
Visitor
428 Views
Registered: ‎07-27-2018

Re: I want to know the delay between I and O in any BUFFER.

Thanks your advice!!

I have additional question for your reply.

I don't know what the STA is. Can you tell me? and What I need is a delay(time) from I to O of OBUF and IBUF. If there is a difference between STA and not, can you tell me that too?

If it is LVCMOS25, is a typical delay value? What does mA mean behind it?

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Scholar watari
Scholar
422 Views
Registered: ‎06-16-2013

Re: I want to know the delay between I and O in any BUFFER.

Hi @tvgod2000

 

> I don't know what the STA is. Can you tell me? and What I need is a delay(time) from I to O of OBUF and IBUF

 

"STA" is abbreviation of  "Static Timing Analysis".

Also you need netlist (NGD file), some timing constraints (UCF file) and timing report file (PAR file).

Would you refer the followings ?

 

https://www.xilinx.com/support/documentation/sw_manuals/xilinx11/ise_c_timing_analysis_overview.htm

https://www.xilinx.com/support/documentation/sw_manuals/xilinx11/pp_p_process_analyze_post_place_route_static_timing.htm

 

> Will you be able to use CMOS as the input buffer other than BUFG, IBUF, and OBUF in LVCMOS25 and push-pull as the output buffer?

 

What do you mean "CMOS" ? If you mean CMOS as "LVCMOS3.3", you should define IO type in UCF file.

If you want to know more detail, would you refer the following document ?

 

https://www.xilinx.com/support/documentation/user_guides/ug381.pdf

 

Best regards,

Visitor tvgod2000
Visitor
414 Views
Registered: ‎07-27-2018

Re: I want to know the delay between I and O in any BUFFER.

I just corrected my reply. Can you answer the second question?

If i 'm using IBUF in LVCMOS25, it is okay to assume that the typical value of delay is 0.82ns?

 

and Are there any elements that only function as BUFFER that connect wires? (except for IBUF, OBUF and BUFG)

 

Thank you for your reply. I'll use the reference material you gave me. Thank you!

 

 

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Scholar watari
Scholar
388 Views
Registered: ‎06-16-2013

Re: I want to know the delay between I and O in any BUFFER.

Hi @tvgod2000

 

What you mentioned is right without output buffer.

In this case (output buffer), you need to consider an extra path delay by load value.

 

> Are there any elements that only function as BUFFER that connect wires ?

 

What do you mean ?

Do you want to know cell delay ?

If yes, it's almost right.

Because, some device has different cell delay between rising and falling.

 

Best regards,

Moderator
Moderator
316 Views
Registered: ‎06-30-2010

Re: I want to know the delay between I and O in any BUFFER.

can you explain why you need this very specific detail, normally customers would just run an STA on the whole design that would take care of these buffer delays, I would select the correct BUFFER for what you need not based on the delay trough it.
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