All Cyclone III devices have a few pins with an unintentional, significantly lower default drive strength than all other pins.
I'm sure Altera will be addressing the issue through an App Note or Errata, but who knows when that will be. In the mean time, if you are developing with any CycIII device, I'd highly recommend developing a boundary scan test (or some other test) up front to see what pins on your device are affected, so that you can reassign pins accordingly if need be. If possible, these pins should not be used for moderate to low impedance loads (such as 1k PUPs or PUDs, or 50 ohm high-speed termination on DDR to a termination voltage). Due to the lower default drive strength, the nets connected to the pins will not reach the appropriate voltage levels in any pre-configuration operation, such as boundary scan testing. After configuration, you're fine. It's just the default drive strength that appears to be the issue. So it messes up preconfig operations on those pins(such as boundary scan testing). I do not know yet what pins these are on other Cyclone III devices in the family, but on the EP3C40780I7, those pins are at least AF18, AH18, and AC11. I can post up any more info as I get it. That'd probably be at least a few weeks sooner than Altera would get around to posting anything. I spent way too much time questioning PCB design, layout, manufacturing, boundary scan test development, test tools, etc, etc before I prompted Altera to look into their part. If you can avoid all that by reading this, great. ---------- Latest response in the on-going thread of a few weeks ... " Hi, The root cause for the incorrect voltage level on the affected pins that mentioned by you is due to the different default drive strength on these pins. We have checked on other Cyclone III devices family and found that all Cyclone III devices are affected. There is less than 10 IO pins that having this limitation for each device. We will have more discussion with other groups on this matter. I will keep you updated once I have more information on this. Thanks & regards,链接已复制
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Cyc III 780 Pin BGA (EP3C40780) complete list of pins affected: AC11, AF18, AH18, AH10, C25, G19.
BSDL files for all Cyc III devices on Altera's site are going to be updated to note the problem pins for each device; that they must be tested in post-config mode if current is needed above about 1 mA. 1149.1 BSDL Revisions at time of this posting: EP3C10's ... 1.01 EP3C120's ... 1.01 EP3C16's ... 1.01 EP3C25's ... 1.03 EP3C40's ... 1.01 EP3C5's ... 1.01 EP3C55's ... 1.02 EP3C80's ... 1.01 EP3CLS150's ... 1.0 EP3CLS200's ... 1.0