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geoffbarnes
Explorer
Explorer
8,051 Views
Registered: ‎09-07-2011

Datasheet

Hi,  does anyone know how to read the "datasheet" min/max report?  Here's an example below for a DDR output interface:

 

Max / Min delays for ports grouped with the -group option
Clocked by: INPUT_CLK
Bus Skew: 0.072 ns
-------------------+-------------+---------+------------+---------+-------+
                   |         Max | Process |        Min | Process |  Edge |
Pad                |       Delay | Corner  |      Delay | Corner  |  Skew |
-------------------+-------------+---------+------------+---------+-------+
FMC_LPC_LA02_P     |   1.043 (r) | FAST    |  0.074 (r) | SLOW    | 0.000 |
FMC_LPC_LA02_P     |   1.043 (f) | FAST    |  0.074 (f) | SLOW    | 0.000 |
FMC_LPC_LA04_P     |   1.115 (r) | FAST    |  0.145 (r) | SLOW    | 0.072 |
FMC_LPC_LA04_P     |   1.115 (f) | FAST    |  0.145 (f) | SLOW    | 0.072 |
FMC_LPC_LA18_CC_P  |   0.976 (r) | FAST    | -0.099 (r) | SLOW    | 0.067 |
FMC_LPC_LA18_CC_P  |   0.976 (f) | FAST    | -0.099 (f) | SLOW    | 0.067 |
FMC_LPC_LA31_P     |   0.986 (r) | FAST    | -0.089 (r) | SLOW    | 0.057 |
FMC_LPC_LA31_P     |   0.986 (f) | FAST    | -0.089 (f) | SLOW    | 0.057 |
FMC_LPC_LA33_P     |   0.971 (r) | FAST    | -0.105 (r) | SLOW    | 0.072 |
FMC_LPC_LA33_P     |   0.971 (f) | FAST    | -0.105 (f) | SLOW    | 0.072 |
-------------------+-------------+---------+------------+---------+-------+
Worst Case Summary |   1.115 (r) | FAST    | -0.105 (r) | SLOW    | 0.072 |
-------------------+-------------+---------+------------+---------+-------+ 

 

Why is the "max" delay associated with the FAST corner, and min with the SLOW.  Shouldn't it be the other way around?   I assume "max" is the Tco max from INPUT_CLK.

 

Thanks

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2 Replies
htsvn
Xilinx Employee
Xilinx Employee
8,038 Views
Registered: ‎08-02-2007

Hi,


As mentioned in page 29 of the http://www.xilinx.com/support/documentation/sw_manuals/xilinx2012_4/ug906-vivado-design-analysis.pdf

 

the datasheet reports out the worst-case numbers. If you would want to report against all the corners you have to use 

 

"report_datasheet -show_all_corners command"

 

Ex:- Timing report attached

 

--HS

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geoffbarnes
Explorer
Explorer
8,005 Views
Registered: ‎09-07-2011

OK thanks.

 

Still a little confused why in my example the worse case MAX delay was in the FAST corner.   As well, the worse case MIN delay was in the SLOW corner.  

 

Could it be related to the MMCM in the clock path adjusting the clock phase?

 

 

 

 

 

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