Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

Cyclone III POR

I have a question about how the POR circuit works on a Cyclone II FPGA. I know there are two different PORs, Fast POR (3ms-9ms) and Standard POR (50ms-200ms). In some of the documentation I see that the Standard POR will allow for a lower power supply ram rate. How does the ramp rate of the power supply effect POR? What if I use Fast POR and have a very slow power supply ramp rate?

Thanks.

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    If you use a fast POR and a slow power supply ramp rate, then you have a risk that the FPGA attempts to start a configuration before the power supply voltage reached its nominal value. In that case there is no guarantee the FPGA will initialize properly.

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    13 years ago

    What kind of power supplies have slow power supply ramp rate and what have fast ramp rate?