Hello. I have a question regarding the parameter of thermal resistance of Junction to case, specified at 1.5°C/W.
The notes state:
RθJC is determined with the device mounted on a 1-in2 (6.45-cm2 ), 2-oz (0.071-mm) thick Cu pad on a 1.5-in × 1.5-in (3.81-cm × 3.81- cm), 0.06-in (1.52-mm) thick FR4 PCB. RθJC is specified by design, whereas RθJA is determined by the user’s board design. (2) Device mounted on FR4 material with 1-in2 (6.45-cm2 ), 2-oz (0.071-mm) thick Cu
I would like to confirm my interpretation of the first note. I interpret this note as follows:
1) TI has derived (measured) the junction to case parameter of 1.5°C/W by using the test conditions cited in note 1.
2) "RθJC is specified by design" means specified for the MOSFET design as opposed to the board design: so I conclude that the junction to case parameter of 1.5°C/W is constant for all board designs, while RθJA varies with board design.
Can you confirm my understanding?
IN our applications. we are using a FLIR camera to measure the case temperature of the MOSFETs under load, and then we would like to use RθJC to calculate the junction temperature, based on MOSFET power dissipation.