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Altera_Forum
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14 years ago

Cyclone IV/EPCS config voltages

When using a Cyclone IV GX device with an Altera EPCS128 serial config flash (in AS mode), is there a preferred voltage for both the flash and the VCCIO of the configuration bank? Looking through the...
Altera_Forum's avatar
Altera_Forum
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14 years ago

If the EPCS chip is close to the FPGA and you have short tracks between the two then there is no problem using 3.3V for the configuration pins, there is very little risk of overshoot.

IIRC the configuration pins don't have clamping diodes, and in that case there wouldn't be any problem driving them at 3.3V with a VCCIO of 2.5V. But if you can I think it's still a better habit to use the same VCCIO than the voltage you use on the I/O pins.