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Altera_Forum
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15 years ago

I/O standard:Different between 3.3V and 2.5V

Hi, In my hardware, I/O standard of most of the ICs connected to CycloneIII are 3.3V, but it also need LVDS connected to CycloneIII. It should to set the voltage of the bank to 2.5V which inc...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

Hi,

as far as I understand the Cyclone III spec. and the Application Note 447 you can connect 3.3V LVTTL/LVCMOS devices to a 2.5 cyclone III I/O bank. So you can power the LVDS bank with 2.5V and connect the other I/Os of this bank to your external 3.3V devices. You should use series termination for all pins which are driven from your external 3.3 devices to your 2.5V I/O bank and you should disable the clamping diode for the input signals in this bank.