Honored ContributorHi, I'm trying to drive a 5-volt device , ie CD-Rom drive, with my Cyclone board and was wondering if it's possible at all? Or does Cyclone only suppport 3.3V at its output pins.
Would it work if i used an Apex 20k which i also have? thanks!!
Honored ContributorYou can use bidirectional level translators or FET switches to protect the cyclone device from 5V supply. By using +3.3V LVTTL or LVCMOS standard, you can meet the minimum input requirements (VIH) of +5V standard (which is usually around 2.4V). By using level translator or FET switch, you can protect cyclone device against pure +5V output from your target device.
Hope this will help. Regards, BDHonored ContributorYou need to look at the data sheet of the other device. Cyclone can drive 5V TTL but not 5V CMOS. Likewise, there are techniques involving the PCI Clamp Diode in order to receive 5V.
Page 11-3 of the Cyclone Handbook details this - http://www.altera.com/literature/hb/cyc/cyc_c51011.pdf Apex 20K (non-E) can drive 5V TTL and 5V CMOS by configuring the output pin as an open-drain pin. You then use an external pull-up resistor to get to a 5V level. Details on pg 46. http://www.altera.com/literature/ds/apex.pdf
