"Psi-JB" and "Theta-JC" are available for Xilinx FPGAs and CPLDs. Are they also available for Xilinx Configuration PROMs?
Xilinx characterizes only "Theta-JA" for our PROM families. This is due to the fact that Configuration PROMs do not contribute a significant amount of heat to a system. Configuration PROMs are only active for short amounts of time, the die does not get significantly hot.
Heat sinks are not required for Xilinx PROMs, and Theta-JC is typically useful only when calculating heat sink parameters. Because measurement of Theta-JA is a worst-case, all-encompassing parameter, no other parameters are required if a heat sink is not used.
Theta-JB and Psi-JB
Because PROMs generate so little heat, the overall effect on the board is negligible. For a detailed explanation of the difference between Theta-JB and Psi-JB, see (Xilinx Answer 9088).