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Altera_Forum's avatar
Altera_Forum
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17 years ago

Disable Diode in Cyclone III

Hi I have a Cyclone III with Vccio=2.5V and want to connect to a DSP with 3.3V Interface. As I understood AN447 I have to disable the diode in Cyclone III. But how can I do this? I read the Qua...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
17 years ago

I think that's not quite correct Cyclone III Handbook says

--- Quote Start ---

The PCI-clamp diode is available for 3.3-V LVTTL, 3.3-V LVCMOS, 3.0-V LVTTL, 3.0-V LVCMOS, PCI, and PCI-X I/O

standards. If the input I/O standard is 3.3-V LVTTL, 3.3-V LVCMOS, 3.0-V LVTTL, 3.3-V LVCMOS,

PCI, or PCI-X, the PCI clamp diode is enabled by default in the Quartus II software.

--- Quote End ---

But you are right in my case. I have 2.5V