hi;
could you explain why a lockup latch is inserted between scan chains with different clocks? and how to stitch two scan chains using a latch with DFTC?
thx
Lock-up latches are necessary to avoid skew problems during shift phase of
scan test. These problems occur if FF’s driven by different clock lines are
connected within a single scan chain.
For this it is recommended to separate scan chains according clock domains.
If not reasonable lock-up latches have to be inserted into the scan chain. To
allow a smooth scan chain stitching on product level it is recommended to
finish each core level scan chain by a lock-up latch.