Tool/software: WEBENCH® Design Tools
I am using the TI webench to design an SMPS.
Vin 20-48 VDC
Vout = 12.2
Iout = 3.5Amps non-continuous. 2Amps continuous.
Tamb = 60C
non-isolated
The design I chose uses the TPS54360. It chose a 20Amp catch diode (STPS20M100SG-TR). I had it optimized for cost. This seems overkill for my application.
I have a 3.5Amp peak current draw, but it will never draw that for more than a second. I would say it would draw 3.2Amps for some DC motors to start up and then go down to a nominal current draw of 2A Max. And the motor will not be on for more than 5 seconds at a time.
Is the STPS20M100SG-TR really necessary? Would I be able to use this diode instead?
Diode: FSV1060V
It has a lower Vf of 0.53V Max. Using equation 37 of the controller datasheet, I get a diode power of 1.6W when drawing 3Amps. With say, a 70W/C thermal resistance JA, that is still a junction temp of 172 C at 60C ambient temp. Even at 2Amps = 1.23W = 146C junction. The FSV1060V is a 10Amp diode, can it really not even handle 2?
That is well over the maximum, but does it really reach that temp if the current is not continuous? What is the best way to get an estimate on my FSV1060V diode whether it is suitable or not? How do you account for non-continuous loads?
Thanks
