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UMall1's avatar
UMall1
Icon for Occasional Contributor rankOccasional Contributor
2 years ago
Solved

VCCIO

I am reading the Cyclone 10 GX datasheet and it seems the device is not capable of interacting with other devices that operate with 3.3V logic. It uses 3V logic. I then come across the following Q&A...
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  • AqidAyman_Altera's avatar
    AqidAyman_Altera
    2 years ago

    In most cases, 3.3V I/O should be compatible with 3V I/O but it should not necessarily work all the system. I think it is safe to check the 3.3V device datasheet first before interacting with the Cyclone 10 GX. It should support as the DC input voltage maximum is 3.3V. In other words, it will support as long as the Vih, Voh, Vil, and Vol of both I/O standards are within the range of Cyclone 10 GX.





FvM's avatar
FvM
Icon for Super Contributor rankSuper Contributor
2 years ago

Hi,
I don't agree that VCCIO needs to be raised to 3.3V to "interact" with 3.3 V devices. That's also well possible with VCCIO = 3.0 V.

You still need to take care to keep the maximum input overshoot specification for signals driven by 3.3V logic. Appropriate termination schemes, e.g. source side series termination should be implemented for longer connections lines.

  • UMall1's avatar
    UMall1
    Icon for Occasional Contributor rankOccasional Contributor
    2 years ago

    How would the commanding of 3.3V logic proceed? Do all 3.3V systems have VOH smaller than 3V?

    Can you confirm that the VCCIO should remain 3V while interacting with 3.3V devices?