Voltage storm IR drop analysis?

[gon8042]

Hi all,

I'm doing voltage storm IR drop analysis embedded in SoC Encounter tool.
When I used Encounter's power tool (power -> early analysis -> simulation-based),
I can see the IR drop by adjusting threshold.

But when I use voltage storm, everything falls into a single bin, no IR drop at all,
regardless of threshold.
What can be problems?
Any suggestions?

 

[gon8042]

Now I have a working one which shows IR drop.
But in some cases, the same error happens.
I looked into log file, and I found something interesting.

During voltage storm analysis, "checking the connectivity of the circuit" shows up,
which is followed by
Connect_size[0] = 1
Connect_size[1] = 248
Connect_size[61] = 40
and more of these.

It seems voltage storm uses only "Connect_size[1] = 248" for analysis,
which means it uses only 248 data values.

But, the working one have only two connect size, for example,
Connect_size[0] = 1
Connect_size[1] = 14244

And it uses 14244 data values for IR drop analysis.

What does the connect_size do here?
And how can I overcome this?