Converter In-Rush Thermistors etc, UPDATE -4

DryCamper11 wrote:

BFL13 wrote:
Interesting about the way the "mass" part of the thermistor works.

So what is the implication between these two, which are both 5R but 20a and 25a where both those amps are well above steady state 13a. The obvious difference is in the greater mass of the MS35, but would that be better? (I have managed to blow both types with hot restarts)

http://www.ametherm.com/datasheetspdf/MS355R025.pdf

http://www.ametherm.com/datasheetspdf/SL325R020.pdf

The MS35 5R025 is wider and thicker. Yes, it has the same resistance, but it can handle 600 Joules instead of 200. Note that the capacitance numbers are also exactly 3 times greater. They get the same resistance, but higher energy/capacitance numbers by using different semiconductor material so the net junction volume is greater, but the net resistance is the same. More junction volume with the same energy dissipated means less heating per junction region and less damage, so the ratings can be higher.

I don't know if I answered the question you asked, but it was my best shot. :)

I am looking at the 2R025s again after reading the latest on all this.
The above says the 355R025 and the 325R020 have the same material but the data sheet says they are both "material (for Beta and curve) H"

the 322R025 is material G though. No idea what is G or H.

http://www.ametherm.com/datasheetspdf/SL322R025.pdf

anyway, the 2R025 has higher capacitance than the 5R020 and more Joules so that is supposed to make it better for inrush, but it does have lower R but is made of G instead of H (is that meaningful?).

So back to the question whether that R number matters for the in-rush stage or just for the steady stage. We have no idea AFAIK what the inrush amount is for calculating minimum R. We do know the spec for the diode bridge 25a 60 where Ken used 170/50 to get that 3.4R

so is the 2R025 out of play unless put in series as 4R, or could the single 2R025 be ok after all?