Yes, I doubt that the volume on a specialty chip like the DS3231 is high enough to attract the counterfeiters.
RS-232 chips and the FTDI USB to serial chips, and consumer FM tuner and audio amplifier chips, is another story. My experience was with a proprietary full custom IC that totally implemented a 'pager' in a single IC package. The Chinese apparently wanted to get into the the paging business, at the time. Of course, the cellphones have now totally eaten the pager business, globally. --- Graham == On Thu, Jul 27, 2017 at 8:21 PM, Pete Stephenson <[email protected]> wrote: > Graham, > > That's very true! > > Still, my past experience with copied chips typically involves a > particular type of RS-232-to-TTL serial converter, the MAX3232. I've > found that nearly all of the ones from unauthorized distributors (e.g. > auction site vendors) are fake, even though the package is marked as > being MAX3232. After a few weeks the chips would fail in a way that > they'd pass high currents and get extremely hot. > > I did a write-up on those chips at > <https://blog.heypete.com/2016/09/11/investigating-fake- > max3232-ttl-to-rs-232-chips/> > and, after decapuslating them, discovered they were completely different > chips on the inside that were made to function the same way as the > MAX3232 (i.e., they converted RS-232 signals to TTL serial, operated on > the same voltages, had the same pinout, etc.). > > In regards to the DS3231, I was concerned that the chip was also a fake > that functioned in the same way as the DS3231, presented the same > registers to the user, etc., but was actually a different design on the > inside. It appears that this is not the case, and in addition to > functioning as advertised, it also is legitimate. If it is a clone, it's > a goood one, but I don't think it is. > > Cheers! > -Pete > > -- > Pete Stephenson > > On Thu, Jul 27, 2017, at 10:34 PM, Graham / KE9H wrote: > > Pete: > > > > If you are concerned about someone copying a chip, you can not rely on > > the > > original manufacturers' markings on the die. > > > > I have experience where the counterfeiter just photocopied the chip > > layout, > > including the original manufacturers marks, and copyright symbol and > > notice > > from the original die. > > > > So, when they copied the die, they really just copied it. Didn't change a > > thing. It was not like they redesigned it, or were selling their own > > design > > with equivalent functionality. > > > > --- Graham / KE9H > > > > == > > > > > > > > On Thu, Jul 27, 2017 at 2:31 PM, Pete Stephenson <[email protected]> > > wrote: > > > > > Hi all, > > > > > > A few days ago I reported the results from letting a DS3231 RTC run for > > > a year, and how the chip kept time well within the published specs. > > > > > > Since I had acquired several DS3231s from dubious sources (Asian > vendors > > > on a major auction site) as part of an RTC module that fits on the > > > Raspberry Pi's header pins, I was doubtful of the authenticity of the > > > chips. I decided to sacrifice one in the name of science and decapped > it > > > at home using alternating heat (a lighter) and cold (a glass of cold > > > water) to embrittle the epoxy casing, then sanded down the back of the > > > chip on fine-grain sandpaper to expose what I hoped was the back of the > > > internals (so as not to damage the die itself). > > > > > > Other than inadvertently sanding through half of the crystal's housing, > > > thus breaking one of the forks of the crystal, this was a success. (I > > > was prepared to decap one in acid had my attempt at physically removing > > > the epoxy package failed.) I slightly scratched the die itself while > > > separating it from the epoxy, but the die itself is clearly visible. > > > Based on a sample size of one and the markings on the die itself, it > > > appears the chip is authentic. The markings on the outside of the epoxy > > > package look a bit dubious and not like typical Maxim laser-markings, > so > > > it's possible the chip was re-labeled at some point. I'll contact Maxim > > > to see if they can look up the lot information. > > > > > > I used my 2 megapixel USB microscope to take some images throughout the > > > process that you might find interesting. The microscope has limited > > > resolution, particularly at high magnification, so some of the photos > > > may not be perfectly clear. I have access to a Zeiss petrographic > > > microscope at my work and will see if I can get some better images > > > tomorrow. I'll try to get high-quality images of the whole chip and > > > stitch them together into a larger composite. > > > > > > Anyway, the photos are available at http://imgur.com/a/0zudj -- I will > > > add more photos from the petrographic microscope tomorrow. I focused > > > mainly on the markings on the die that indicated it was, in fact, a > > > Maxim chip but if there's any other region of the chip that you'd like > > > images of, please let me know and I'd be happy to take some more > > > pictures. > > > > > > I hope you find this as interesting as I did. > > > > > > Cheers! > > > -Pete > > > > > > -- > > > Pete Stephenson > > > _______________________________________________ > > > time-nuts mailing list -- [email protected] > > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > > > mailman/listinfo/time-nuts > > > and follow the instructions there. > > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
