I am using the Xilinx based FPGA. Xilinx datasheet suggest the theta ja value is 7.3 °C/W and power dissipated is nearly 50W and ambient temperature at which it is operated is 85
Junction temperature= ambient temperature + thermal resistance (theta ja)power dissipation
= 85+ 7.3*50
= 450°C
Is this junction temperature is expected or some mistake in the consideration. Anybody who worked on thermal analysis can help me out. Xilinx XPE shows the effective theta ja is 1 °C/W. I am not understanding why they have consider 1 in xpe and 7.3 in datasheet. How Theta ja will vary?
Also i want to understand what is the relation between the theta ja, jc, jb
Also as per my understanding,
Materials that are good conductors of heat (metal) have a low thermal resistance
Materials that are poor conductors of heat (plastics) have a high thermal resistance
But i want to understand why we are adding this instead of subtracting to reduce the thermal resistance
Theta ja = Theta Jc + Theta ca
Any insight would be greatly appreciated.