XC9500XL device (any density) fails to configure (load) properly immediately following power-up. What could be causing this?
Check the power supply ramp rate. Xilinx CPLDs, as well as all other CPLDs, will configure properly only with a monotonic power supply.
Xilinx has found that some earlier XC9500XL devices (with a date code prior to 9949) have exhibited an additional sensitivity to non-monotonic power supplies. This increased sensitivity, combined with the duration, profile, and monotonicity of the power supply, could cause the device to configure incorrectly.
The device will configure correctly when given a JTAG configuration command via the JTAG Download Cable. This is most easily done by issuing a VERIFY command from the JTAG Download Software.
Devices with a date code of 9949 or greater do not exhibit this additional sensitivity. If you are experiencing configuration problems with any XC9500XL device, please contact your local Xilinx salesperson for appropriate device dispositioning and/or replacement.