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I am using a Cyclone 3 EP3C10E144C7N chip that is mounted on a third party board (the schematics of the board is attached in the file DB3C10.pdf). This board's I/O pins are interfacing with the I/O pins from a MAX EPM7128S PLD chip.
After using this setup for a few weeks, my C3 chip suddenly died. I found that one of the IOBank pins, as well as the VCCINT pin, is shorted to ground. Thinking that it was bad luck on my part, i replaced the board with another one. However, a few weeks later, my second C3 chip died as well! This time, a different IOBank pin, as well as the VCCINT pin, was found to be shorted.
I currently have no clue what might have caused my C3 chip to be damaged. I am connecting the I/O pins of the MAX chip directly to the I/O pins of the C3 chip. The MAX chip's VCCINT is set to be 5V, and its VCCIO is set to be 3.3V. The C3 chip's VCCINT is set to be at 1.2V, and its 8 IOBANKS are all set at 3.3V. I did not take note of the current flowing into the C3 from the MAX chip.
Any enlightenment on this issue would be very much appreciated.
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Hi,
check the default setting of unused pins. At least older versions of Quartus are setting unused pins to "Output driving Ground". I'm not sure that Cyclone 3 devices could directly connected to 3.3V signals. Check in the datasheet.
Kind regards
GPK
Honored Contributor
