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ssampath
Voyager
Voyager
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Registered: ‎10-12-2016

Hold time violation on asynchronous reset

Hi Friends, 

I am getting hold violation on reset net, this reset is static signal indirectly this is am providing from VIO at top level. but internally this is connected to FF. 

 

Can i neglect this violation ? 

When we can ignore the hold violations ? 

what modifications we have to do to overcome hold violations ?

 

hold violationhold violation

NOTE: Any help or suggestions are highly appreciated. 

Thank you 

S Sampath 

-Sampath
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1 Reply
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Registered: ‎01-22-2015

@ssampath

From your reset name (poreset = power-ON reset?), it appears you are sending a power-ON reset to the various components of your design.  Often, power-ON resets are asynchronous and they cross clock-domains - both of which can cause timing analysis problems.

Usually, a circuit called a reset-bridge is used to bring the power-ON reset into each clock-domain.  That is,  a separate reset-bridge is needed for each clock domain. The reset-bridge causes the reset in each clock-domain to go ON simultaneously with the power-ON reset and to come OFF synchronously with the clock in the clock-domain. The reset-bridge also acts as a synchronizer and should prevent the timing analysis problems you are seeing. You’ll find details of the reset-bridge and other discussion of resets in <this> post.

Mark

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