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Old 01-01-2005, 03:38 AM
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Default Dead FPGA?

Recently I assembled a board containing (among other things)
a Spartan-IIE 300. Unfortunately, after I powered on the board
I discovered that both the 1.8V and the 3.3V power rails were
shorted to ground. After much head scrating, I realized that the
FPGA (in the PQ208 package) was rotated 90 degrees... (sigh).

I removed the FPGA and re-installed it in the proper position.
Now the 1.8V and the 3.3V rails are no longer shorted to ground,
but the resistance between the two rails is only 4.4 ohms and the
1.8V rail is reading about 2.9V. The regulator put out 1.8V after
I had removed the FPGA before putting it back on again the right way.

Is there any hope for this device, or should I just give up and
replace it? Does this sound like a known failure mode if the
power and ground pins on the device have previously been connected
to the wrong potential? Any other ideas?
Thanks in advance for any replies.

-Ewan

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Old 01-01-2005, 07:25 AM
Bob
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Default Re: Dead FPGA?


<[email protected]> wrote in message
news:[email protected] ups.com...
> Recently I assembled a board containing (among other things)
> a Spartan-IIE 300. Unfortunately, after I powered on the board
> I discovered that both the 1.8V and the 3.3V power rails were
> shorted to ground. After much head scrating, I realized that the
> FPGA (in the PQ208 package) was rotated 90 degrees... (sigh).
>
> I removed the FPGA and re-installed it in the proper position.
> Now the 1.8V and the 3.3V rails are no longer shorted to ground,
> but the resistance between the two rails is only 4.4 ohms and the
> 1.8V rail is reading about 2.9V. The regulator put out 1.8V after
> I had removed the FPGA before putting it back on again the right way.
>
> Is there any hope for this device, or should I just give up and
> replace it? Does this sound like a known failure mode if the
> power and ground pins on the device have previously been connected
> to the wrong potential? Any other ideas?
> Thanks in advance for any replies.
>
> -Ewan
>


Replace the FPGA, and any other device that uses the 1.8V supply. The FPGA
was obviously internally shorted between VCCINT (1.8V) and whichever pins
were hooked up to the 3.3V supply (VCCO and/or VCCAUX).

Bob


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