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Altera_Forum's avatar
Altera_Forum
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10 years ago

Cyclone IV fails to configure below -20C

I have a Cyclone IV design that operates correctly down to -20C but fails to configure below that temp. I have attached the schematic for the configuration block along with a scope trace showing co...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
10 years ago

The reset controller looks like the culprit to me, or the 3.3V rail (which you didn't measure above). Just to isolate the problem, can you lift a lead on the reset controller so it can't pull nCONFIG low, then configure the part via JTAG in the failing temperature range?

One other thing to note is that you've got the MSEL pins set for the fast POR delay. According to the CIV handbook: "The fast POR time option has stricter power-up requirements when compared with the standard POR time option." This could be something to look at, but it would not cause the reset controller to keep pulling nCONFIG low. That still points to the reset controller.