We intend using MP8795H to generate 3.45V with a DC load current of 14A.
We are trying to figure out the maximum junction temperature for the IC given our operating conditions.
If we assume that we have a similar board setup as the evaluation board what is the “effective” ΘJ****A for the system (thermal conduction from the case
Of the device to the PCB copper and thermal radiation from top of package?)?
With reference to Thermal results graph on the Sheet 8 of the datasheet;
- Are these graphs with respect to the Evaluation board?
- Is the Case temperature being referred to that of the temperature of the Pgnd pin?
- The evaluation board has 4 layers. Is it 2oz copper on each layer?
- Looking at the 5V graphs. For Iout of 10A the case temperature increases by about 30 degrees and the efficiency is in the order of 95%.
- So for a 50W output @ 95% efficiency approximately 2.45W being dissipated by the MP8795H (since only 175mW dissipated by the
inductor as calculated by RedExpert from Wurth). So as a rough approximation the case temperature rise is increasing at a rate of 12.2 Deg C/W.
Is this the “ effective” ΘJ A for the evaluation board.
- So do we infer that the junction temperature is ΘJC X Power dissipated above this i.e. 2.45 x 4 = 9.8 degrees above the case temperature?
- Is there any significant thermal benefit in trying to attach a heatsink to these devices or is the majority of the heat dissipation through the pins/pads?