On Wed, 29 Aug 2018 at 16:17, Sean Breheny <shb7@cornell.edu> wrote:

....
When charging a cap through a resistor from a constant voltage source, the
I2t is equal to 0.5*(1/R)*C*V^2 where R is the resistance in ohms, C is the
capacitance in Farads, and V is the source voltage. For your case of
charging a 100uF cap through 0.34 ohms (as Russel found) from 15V, the I2t
is 0.0331 amps^2 seconds. Looking on Digikey at 750mA fast picofuses, I see
two values for melting I2t: 0.041 and 0.15. Notice that both of these are
higher than the value in your case. However, the 0.041 value is
uncomfortably close,

Adding  a say 1 Ohm series input resistor (as suggested in my prior post)
would give you the i^2t margin that Sean recommends and add only about 0.3
V drop under your typical peak current.  Adding slightly more (say 1.5 Ohm)
would give you in excess of that margin of error for caps with any ESR
(including 0 Ohms).

Russell
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