If I do not specify an I/O standard constraint on user I/Os, which I/O standard will be used?
- For Spartan-II and Spartan-IIE devices, the default I/O standard is LVTTL, 12 mA, slow slew rate.
- For Spartan-3/-3L/-3E devices, the default I/O standard is LVCMOS 2.5V, 12 mA, slow slew rate.
Differential I/O standard:
- Spartan-II devices do not support the differential I/O standard.
- To instantiate the differential I/O standard in Spartan-IIE devices, refer to the data sheet at: http://www.xilinx.com/support/documentation/data_sheets/ds077.pdf
- For Spartan-IIE devices, the default differential I/O standard is LVDS 3.3V.
- For Spartan-3/-3L/-3E series devices, the default differential I/O standard is LVDS 2.5V.