This little BASTARD cap...
So I’m putting together my parts list for the 54645A, and I can’t find a schizzmatic or component level parts list to save my life.
Of COURSE, this is the side jammed up tight against the heat sink so I can’t tell what voltage, and parametric search on DigiKey returns bupkis for this value in the current P561 product line.
So I bite the bullet and remove the little stinkbomb; it’s a bit of a PITA due to silicone spooge entanglement, but not too bad. I keep telling myself.
I get my numbers, and I look for anything close available locally, but no. Gonna have to order. *sigh*
I go about cleaning up the pads on this and another bastard cap that was completely obfuscated with a heat-shrink wetsuit, and the ground pad is just a complete dicksore to get clear. Tried solder-wick multiple times, even dipped in flux, tried solder-sucker several times and finally got it by propping up the board on edge so I could get sucker on one side and big chisel iron on BOOST contacting the other side. That GND fill was just sucking away the heat like a vortex.
So now I want to put it all back together until parts arrive... and I realize I do NOT want to do that desoldering job ever again for fear of cooking the PCB to death.
Fuck me. With a shovel. Sideways.* ![Banging Head |O](https://www.eevblog.com/forum/Smileys/default/bangheadonwall.gif)
mnem
*in the room. I may be a perv, but I’m not suicidal. ![Tongue :P](https://www.eevblog.com/forum/Smileys/default/tongue.gif)
Okay... looking to find a sub for this little bastard; I was thinking of going to Y2 poly, and I've found a EPCOS MKP B3202 series that should just fit while having a lot more headroom.
The manufacturer recommends this line for SMPS DC conversion applications, which is good, as this one is right across the gate/source of a big ol' IRFPC50 MOSFET in the first DC converter.
The only problem I see right now is that from experience these tend to have pretty low ESR, often similar to ceramic, so even for a 47nF I'd still expect ESR of 1Ω or less. The one I just took out measures 40Ω ESR. Can't tell from the datasheet if that's in the normal range or not.
![Banging Head |O](https://www.eevblog.com/forum/Smileys/default/bangheadonwall.gif)
I know these can be used as drop-in replacements for the dread RIFAs in AC line applications; I've seen it oodles of times. But here I'm concerned about low ESR affecting the stability of the SMPS at these higher frequencies.
Opinions?
mnem
![Broken! :-BROKE](https://www.eevblog.com/forum/Smileys/default/smiliey_scope_broke.gif)