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MFerr15's avatar
MFerr15
Icon for New Contributor rankNew Contributor
6 years ago
Solved

Hi, I´m using a Cyclone 10 (10CL040YU484I7G) in a new design can I pull-up this pins CRC_error and INIT_DONE to a 5V rail

INIT_DONE is a open-drain and in the Pin connection guidelines says that

"When using this pin, connect it to an external 10-KΩ pullup

resistor to an acceptable voltage for all devices in the

chain that satisfies the input voltage of the receiving

device. When not using this pin, it can be left floating or

tied to GND"

The Input voltage receiver in my design is 5V, can I pull-up this pins to a 5V rail?

And for the CRC_error pin is state the same as for the INT_DONE.

INT_DONE is a Open-drain and the CRC_ERRO is only I/O Output

Best Regards

2 Replies

  • ak6dn's avatar
    ak6dn
    Icon for Regular Contributor rankRegular Contributor
    6 years ago

    Absolute Vi max for this family is 4.2V for pins, so the simple answer is no you cannot connect these pins to 10K pullups to 5V without causing possible device damage.

    You will need some circuitry (diodes, resistive divider, voltage conversion buffer) to connect your 5V device input to what is basically a 3.3V compatible I/O.

    Depending on your 5V device technology a pullup to 3.3V may, or may not, produce an acceptable high level. If it is 5VTTL, yes; if it is 5V CMOS, likely not.

    Google '3.3 v to 5v level conversion circuit' there are lots of documented ways to do this with both off the shelf devices or discrete circuit components.