I am using CoolRunnerII CPLD and wish to know what is the I/O Voltage Standard setting in the fitting properties:

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I know that Vcc must be 1.8V. I also know that I define the IO bank voltage by providing externally voltages to Vccio1 and Vccio2. So, what exactly is the IO setting in the fitting process configures?


The I/O standard you choose depends on what the CPLD is hooked up to. If you hook it up to a 1.8V device, you should supply 1.8V through Vccio1 and Vccio2 and select LVCMOS18 (for low voltage complementary metal oxide silicon integrated circuit chips running at 1.8V). For other I/O voltages you can choose the standard accordingly.

  • \$\begingroup\$ Well, the Vcc power for this device is 1.8V. Now, I have two Vccio banks. Say, I want bank1io to be a 3.3V and bank2io be at 1.5V. However, I can only choose one of the standards above. \$\endgroup\$ – Nazar Jun 18 '14 at 13:43
  • \$\begingroup\$ As you can see on page 3 of the Specs you posted, it is no problem to run the core of the CPLD at 1.8V and the I/O drivers at higher voltages (-0.5V to 4V). The I/O pads are obviously driven with separate rails and contain level shifters. So you can run them at higher voltages than the core. If you have different I/O voltages, you either manually allocate them to the according pins (separate banks) or let the fitter do the job. More info: japan.xilinx.com/support/documentation/sw_manuals_j/help/… \$\endgroup\$ – Brandli Jun 23 '14 at 15:30
  • \$\begingroup\$ Why is it so hard to fit it in my head? Still can not get it. If I externally hook up Vcc=1.8V, Vccio1=3.3V and Vccio2=1.5V, what should I choose for the setting? If I understand correctly, the half of the pins are assigned to bank 1 and the other half to bank 2. So, regardless what I do, the voltage on the pins will be the same as the voltage of the bank to which they belong to. Right? \$\endgroup\$ – Nazar Jun 24 '14 at 13:13

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