I agree - but said resistor should be a pulse-withstanding type :) On Wed, Aug 29, 2018 at 3:08 AM RussellMc wrote: > On Wed, 29 Aug 2018 at 16:17, Sean Breheny wrote: > > ... > When charging a cap through a resistor from a constant voltage source, th= e > I2t is equal to 0.5*(1/R)*C*V^2 where R is the resistance in ohms, C is t= he > 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 I2= t > is 0.0331 amps^2 seconds. Looking on Digikey at 750mA fast picofuses, I s= ee > 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 Oh= m) > would give you in excess of that margin of error for caps with any ESR > (including 0 Ohms). > > Russell > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .