Hi ADI Expert,
I use ADM1278 Design Worksheet Tool to design serve power system.
But I have one questions about PSET.
It show maximum and minimum value of suggested PSET, may you please share how to calculate these two value?
I know the concept to take care of power limit but the value I calculate I can't match with value suggested by tool.
The PSET max clamp limit is the smallest current that a clamp can take on, taking into account resistor tolerances and ADM1278 variation. It is calculated with the max clamp value and the max Vin value. You have to choose a PSET limit larger than that (line 298).
The PSET max SOA limit comes from your SOA calculations, and represents the maximum amount of power that your FET can handle in the time-out interval. It is calculated as the smallest Vin operating voltage times the derated FET current from your SOA analysis.
The PSET max system limit comes from the maximum voltage that the PSET pin will accept (nominally 1.5V). You cannot set PSET higher than this number, and if it is lower than the PSET max SOA, then it is used as teh max limit.
Thank very much for your feedback, it's very clear and helpful!