Converter In-Rush Thermistors etc, UPDATE -4
UPDATE on 17 Nov, Update 2 on 22 Nov, Update 3 on 16 Jan 14, Update 4 on 19 Oct 14. --------------- In a recent thread there was mention of how you can wreck your gizmo (in my case a converter) ...
Forum Discussion
lorelec wrote:
"Inrush current limiters must not be
connected in parallel.
This is what I learned. Even if the thermistors are very closely matched - closer than it's possible to measure - they won't stay matched. They change their resistance as they heat up. One will get slightly more current, even if it's due to the length of the legs soldered into the board. The lower resistance heats more, and then draws more, and before you know it, it's been driven well beyond its specs (assuming you thought to split the current between the two components.)
By their nature, they just don't play well in parallel. One will grab the entire current. You'd be fine if both thermistors could handle the entire current load, but then why bother to use two.
