Output I/O Standards which are not supported in Banks 0 and 2 (top and bottom):
LVCMOS25 24 mA Drive
LVCMOS18, LVCMOS18_JEDEC 24 mA Drive
LVCMOS15, LVCMOS15_JEDEC 16 mA and 12 mA Drive
LVCMOS12, LVCMOS12_JEDEC 12 mA and 8 mA Drive
Output I/O Standards which are not supported in Banks 1, 3, 4, and 5 (left and right):
* LVPECL25 and LVPECL33 are not supported as an output in any bank on Spartan-6 FPGAs.
In addition to these standard rules, there are Bank Compatibility rules based on VCCO voltage and other I/O Standards used which must be followed. Those are not covered in this Answer Record. The following sections should be closely read for I/O banking rules in the Spartan-6 FPGA SelectIO Resource User Guide: