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Altera_Forum
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14 years ago

nConfig drops during power up and stays low after on Cyclone3 EP3C5E144

Hi All, i have a design using Cyclone3 EP3CE144 device, and the JTag programmer (USB Blaster) can't scan or find the device. The symptoms are: The device can't be scanned by programmer (USB...
Altera_Forum's avatar
Altera_Forum
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14 years ago

This is what happens when the exposed "E-PAD" on the bottom of the E144 package is not connected to GND. This is a functioning ground pad and must be connected to ground for the device to work (not just for thermal dissipation).... if not device never exits POR and JTAG is not functional....

I've seen this a hundred times.... you will need to connect the E-PAD to ground to get it to work whether by removing the part, attaching wire or contact and remounting (also make sure no shorting to exposed vias, etc) or very carefully drilling through PCB to bottom of package to attach wire... neither of which are quite trivial rework. Longer term, you will need to spin the board.

Good luck,

-Chriis