It is to be noted that you will never find scan paths originating at positive edge-triggered flop and ending at negative edge-triggered flop due to DFT specific reasons. Needed where the path starts at a positive edge-triggered flop and ends at a Since, lock-up latches are inserted for hold timing these are not Latch? It depends on the path you are inserting a That is why lockup latches can be referred as as the soul mate of scan-based designs. Have been high as there a large uncommon path between the clocks of the twoįlops leading to large on-chip-variations. ![]() Lockup latches, it would have been very difficult for STA engineer to close Scan-shift mode, these interact shifting the data in and out. Hence, the clock of these twoĭomains will not be balanced and will have large uncommon path. For instances, the launching and capturingįlops may belong to two different domains (as shown in figure below).įunctionally, they might not be interacting. That is why, lockup latches are used to connect two flops in scanĬhain having excessive clock skews/uncommon clock paths as the probability of Is very large and meeting hold timing is a challenge due to large uncommonĬlock path. More than a transparent latch used intelligently in the places where clock skew Problems during shift phase of scan-based testing. Lock-up latches are necessary to avoid skew Latch is an important element in scan-based designs, especially for
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