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LOCKup & SYNC Registers.

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pandit_vlsi

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lockup latch

Hi all.
1.what are LOCK-Up flops/latches and sync registers?
2.when they are used?
3.what is the advantage?

Providing pictorial explanation is appreciated.


thanks a ton,
pandit
 

cheelgo

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lockup latches

Hello pandit_vlsi,
lockup ff/latch used to get the data latched sometimes to remove clock skew when datapath will cross over clock boundary.
sync. register which MTBF have to be guaranteed for the signal which cross boudnary.
add comments, please
 

questionmark

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functional lock up latches

should be Mean Time Between Failure. Sync registers can be used to pass signals from one clock domain to another asynchronous clock domain
 

nine8

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functional lock up latch

lock-up latch is used in DFT, it 's the solution for the hold time violatiion .
add lock-up latch in the scan -chain
 

saqibrashid

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what is functional lockup latch

Hi,

Can I add two more queries to the same question.
1) In functional mode, when crossing clock domains we used sync-FF. In Scan mode, if we connect FFs from different clock domains in same chain, why don't we have to use sync-FFs. Metastability problem should also be there in scan-mode even though clock freq is low.

2) In scan-mode we use lock-up latches if we have to stitch FF from different clock domains in same scan chain. What trick does lock-up latch do in scan mode that we don't have to do in funcitonal mode. I mean why don't we have to use lock-up latches in funcitonal mode.

Regards
 

devop

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hi
here's a lockup latch question here~~~~

If we don't add the latch in che chain,
in test mode,if here's hold problem, p&r tool will add the delay cell here,
so the latch is not necessary

am I right????????????????
 

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