AR# 1308: CPLD XC9500/XL/XV CoolRunner-II/XPLA3 - What is the maximum power dissipation allowed with Xilinx CPLDs?
CPLD XC9500/XL/XV CoolRunner-II/XPLA3 - What is the maximum power dissipation allowed with Xilinx CPLDs?
What is the maximum power dissipation allowed with Xilinx CPLDs?
The limit is based on the amount of heat that a device can tolerate; this is dependent on the device and package selected. For more information on calculating the maximum power dissipation, see the Device Package User Guide (UG112).
The relevant section is "Thermal Management & Thermal Characterization Methods & Conditions" -> "Thermal Data Usage" and includes examples on calculating the maximum junction temperature.
Xilinx CPLDs have a maximum junction temperature of 150 C; however, timing is guaranteed only up to 70 C for Commercial and 85 C for Industrial temperature grade devices. By substituting in the maximum junction temperature, you can solve for power.
Xilinx recommends mixing outputs to have Slew Rate Limited (SLOW) mode along with outputs in Fast mode. This recommendation reduces ground bounce that can be caused by a large number of outputs switching simultaneously. For directions on setting slew rates, see (Xilinx Answer 983).