I am designing a reverse polarity protection using the LM74610 chip.Now, my circuit can take peaks of about 90Amps and constant of 50-52Amps. This is quite a load and I want to select the right MOSFET. I have been thinking of the GaN MOSFET family for this application. The requirements -
VDS - 24V, Id - 50Amps, 90Amps (peak bursts).
Now, my thermal calculations are as stated -
Rja = 42degC/W. => Temperature = 42*3.75 = 157degCel. This is beyond the operating temp. So, I will need immense amount of cooling for this. Also, in the maximum ratings they have mentioned a factor of 6degCel/W for 90Amps continuous current. How is this achieved ? I cannot go beyond the 1sqinch,2Oz FR4. So, will this be a bad choice ?
Is using such MOSFETs in high current applications unadvisable ? Can anyone suggest a different MOSFET ?
I then decided to check the PSMN1R0-30YLC MOSFET. This has even lower Rds. But the thermal Rja is not mentioned. Also, the graph below shows that I can use it in DC mode for 24V for drawing only 1.5Amps only. Please check graph below -
So, using MOSFETS the bets approach in such applications ? Can I us 2 MOSFETs to split current flow ? I know it wont be ideal but even if some level of splitting is achieved it is good. I can use 2 GaN MOSFETs to do it.