man i hate when that happens. it's happened to me once before with a seller from china too. here's what i used to try and tell if the IC or transistor for that matter as soon as i get in an order.
i've got a few chinese ebay sellers that are actually reliable, at least so far. one big key that throws me to thinking the part is fake is i look closely at the pic to see if it looks sanded, and look at the printing. if it looks kinda questionable i skip it. also, i don't know these ones cost you, but i also go by the price. i try to get a good deal, but if it's too low i skip it, like the case with anything from polida. as soon as i get them in i test a few out in a build that works, if there's issues (sounds off, squeals, etc.) i fire off an email to the seller.
also, for chinese sellers i check their rating, anything below 99.5 i skip them, and look at recent feedback to see if there's any red flags.
I've had a lot of problems with 7660S and 1054 from Tayda squealing. One weird thing is that the pitch changes when I touch the IC with my finger
I'm close to being done messing around with the things. Just so problematic.
One question, did you have more than one charge pump powered up on the same power supply? If you have two high frequency oscillators like a pair of charge pumps, you can get issues with heterodyning where the two frequencies combine to make a lower (audible) frequency
no prob mao. just started it a few days ago, so by all means add whatever you can.
kinski - i used to get good parts from polida and ordered from them fairly often. i did this up untill a few years ago once everyone started getting a lot of bad parts, and since then i've blacklisted them so to speak.
Tayda advertises some ICL7660CPAZ - no "S", so no frequency boost. I bought a couple, they work but squeal, but the chips are labeled SCPAZ. So somebody faked the "S" part, but Tayda is listing them correctly as no-boost. Perhaps they got stuck with the fakes. But it would certainly be confusing if one fished the chip out of a stash later and went by the labeling.
If you are in the US, Smallbear sells TC1044SCPA that are just as cheap as you can get any of the other charge pumps, and should be reliable.