i am finding Short between VCC and GND pins of EP1K100 ACEX Series IC. What could be the reason other than ESD on I/Os which could lead to this .. any idea..?

[NReddy]

To confirm this i have taken out all passives between power rails of IC and other connecting devices on Board but still there is short in power rails ( 2.5V and 3.3V) of IC .

[JScho6]

I tkae it that you did not intend to open a new thread, but wanted to answer yesterday's thread?

Anyway, once the chip is showing this kind of damage, it's dead for good, not way to re-vive it. Did you check the design for use of 5V signals that possibly drive into clamping diodes that you may have switched on by accident?

Jens

[NReddy]

Hi Jens,

Thank you for the answer..

You are correct..that I was trying for premier support...so posted it again by mistake..​

And Yes I have checked design for 5V tolerent ​ standard and it is designed for 3.3V standard.

And if I am not wrong, if this is due to quartus design issue then problem should be consistent rt...?

Sorry forgot to mention in post...FYI..it is happening ​only in around 10% of boards i.e 8/80 boards..

[JScho6]

If this is only happening on a few boards, then you're probably looking for a different cause. The defect you're describing may be a latch-up, which means that both the push and the pull driver of the CMOS output are driven at the same time, shorting out the IO voltage to GND.

I have hardly ever seen this on an FPGA. but I've seen it many times on CPLDs, ever since the AMD MACH series. The most likely cause for a latch-up on CPLDs is power spikes and drops. Check voltage ripple and step response on your regulators. You can always improve step response with a larger cap and lower ESR, but with multiple voltages involved on an FPGA board, you may need to go into deeper analysis for possible cross-regulation problems.