This is probably a stupid question and it was probably asked before but I searched and couldn't find any occurrence.
If decoupling capacitors need to be as close as possible to the IC they are protecting, why are they not integrated to ICs?
I am sure there is a good reason and looking forward to find out.
Two good reasons. Size and cost. Integrating a capacitor would make the IC package much larger and more expensive since practical cap sizes used to decouple ICs are much larger than the IC chip itself.
Well, for higher speed apps etc, the capacitor required may need to be accurately calculated. Also PCB requirements may drive the need for compound bypassing.
Fair enough, I was under the impression that within an IC there were already some caps but I guess not.
While I am at it, is it acceptable to place a surface mount cap under a DIL IC on the same layer that is, as the IC pins are long enough for the chip to sit on the cap?
Well, for higher speed apps etc, the capacitor required may need to be accurately calculated. Also PCB requirements may drive the need for compound bypassing.
Fair enough, I was under the impression that within an IC there were already some caps but I guess not.
While I am at it, is it acceptable to place a surface mount cap under a DIL IC on the same layer that is, as the IC pins are long enough for the chip to sit on the cap?
We usually call it a DIP, not DIL. From an electrical standpoint, there would be no reason to not do it. From a maintence standpoint, I think it would not be wise. Very often, the caps are installed on the opposite side of the board, under the IC.
We usually call it a DIP, not DIL. From an electrical standpoint, there would be no reason to not do it. From a maintence standpoint, I think it would not be wise. Very often, the caps are installed on the opposite side of the board, under the IC.
Actually I always call it a DIP but I guess I had DIL in my head as I was just adding some devices to a schematic in Eagle and they call it DIL.
My question originated from a circuit I did with the goal to have the cap on the other layer under the chip but I forgot to switch its layer and it is when came the time to solder that I had realized my mistake, that's when I figured it still had a nice fit under a DIP chip.
About maintenance issue does a 0.1µ cap ever go bad?