Charge Pump Question.

[JakeFuzz]

I pulled the classic mistake of ordering the wrong charge pump from Mouser for my Sunking build. They sent me a Maxim ILC7660CPA+. Has anyone tried this chip in a roadrage? I am wondering if that high pitched squeal will be present in whatever I am powering with the RR. Ideally I would like to swap out the chips and avoid ordering another.

[JakeFuzz]

Well, I sort of answered my own question. I didn't realize how quick of an experiment this would be. The squeal is still present but only very faintly audible with the volume (tested with the timmy) totally maxed out. I also have a switch to a 15 volt regulator on my conversion boxes. While running in 15 volt mode there is no squeal at all. I think ill leave it in the RR for now until I can pick up the correct chip but I hope that helps anyone who was wondering what to do with their mis-purchased charge pumps. 

[cjkbug]

ya beat me to it. I used that chip in a road rage and got a squeal out of a buzzaround clone.

[stecykmi]

You could try increasing filtering caps (C18, C21) a whole lot (like maybe 100uf or more, as big as you've got). Also try putting a smaller poly film cap in parallel with either. Poly film caps have an easier time with high frequency noise than electrolytic. That said, the audio range isn't very fast at all so you may be okay with just an electrolytic.

Even if doesn't really help, there's no harm in sticking them on there (i probably would if i had the correct parts if i were to build one).

Also, C19 can also be increase to 10uf. It deals with voltage conversion efficiency, I believe. The roadrage uses 10uf.