Tool inserted DFT lockup latch is not transparent in functional mode (no test port)

[Ashish Agrawal]

Hello,

I am using genus tool for synthesis. I have the 2 different clock domains in my design but connecting the whole design into single scan chain.
I see tool insert a lockup latch when it is stitching the scan chain from one domain to another domain.

The tool inserted negative level lockup latch doesn't have any test port. It has only D,Q and E (enable) port. And the E is connected to clock1 itself.
shouldn't the latch be transparent during functional mode? Is there any constraint which I can add so that tool can insert the lockup latch with test signal?


Thanks in Advance.

[Tieny]

Hello,

I am using genus tool for synthesis. I have the 2 different clock domains in my design but connecting the whole design into single scan chain.
I see tool insert a lockup latch when it is stitching the scan chain from one domain to another domain.

The tool inserted negative level lockup latch doesn't have any test port. It has only D,Q and E (enable) port. And the E is connected to clock1 itself.
shouldn't the latch be transparent during functional mode? Is there any constraint which I can add so that tool can insert the lockup latch with test signal?


Thanks in Advance.

Hi ,

The lockup latch only active in scan shift path (FF1.Q -> LU.D -> FF2.SI ).
So dont care about it on functional mode.

Tiep Ngo

[Sunilverma03]

Hi,
Lockup latches do not have testability features. It will be ignored during normal functional mode, since the output of this latch will go to SI of next FF(Clk domain 2), Which will be disabled during functional mode.

Sunil