we are running in trouble with our curent design for a Xilinx Spartan 3 xc3s1500.
It does signal processing and it seems that sample got lost with increasing temperature. Immediately after power on all works well, some minutes later, if final temperatures is reach, some samples are missed. I hadn't a thermometer ready, but I can always touch the FPGA for a long time, it may be 50=B0C. It runs with a clock of 76.8 MHz, PAR states a maximum frequency of78.777MHz, and logic utilization is about 60%.
One board works as expected and two other show the explained effect, the boards have the same layout but are made by different manufacturers. At least the not working are lead free.
Just now, we had a discusion to the influence of temperature to propagation delay. I don't believe that it influences clock lines and other logic resources in a (big) different way. Is It true or not?
I read the thread "Propagation delay sensitivity to temperature, voltage, and manufacturing", but the answers are very related to DCMs.