The price difference could be explained by LCSC purchasing in bulk directly from TI or similar and selling them at lower margins because their volumes are larger. I've seen "clone" chips sold at LCSC, but they're listed under a different brand (I can't recall one off memory unfortunately).
How bad can a $2.97 ADC be?
11–20 of 141 posts
Re: How bad can a $2.97 ADC be?
#12Earlier quoted context omitted.
It may not even be a clone. As the author said, it could just as easily be production line items that were tested and found to be outside of spec tolerances and resold off-label.
TI makes all their analog stuff in house so that's unlikely. That's far more common for fabless companies that send their parts off to an outside fab.
What does TI do with their out-of-tolerance products? Straight in the garbage?
Re: How bad can a $2.97 ADC be?
#13The price difference could be explained by LCSC purchasing in bulk directly from TI or similar and selling them at lower margins because their volumes are larger. I've seen "clone" chips sold at LCSC, but they're listed under a different brand (I can't recall one off memory unfortunately).
Never had bigger issues ordering from LCSC. And I buy a lot of stuff from them.
Re: How bad can a $2.97 ADC be?
#14> So what’s going on with the cheap parts? My best guess is that these are either quite good copies, or failed parts that somehow made their way into the hobbyist supply chain. The vast majority of counterfeit chips I've seen were from ghost shifts but IIRC TI fabs all their analog parts in house, I doubt they're ghost shift parts or failed QC. I think its probably a relabeled ADS1015.
Interesting, most of the counterfeits that affect me (eg. FTDI, STM32 clones) have been just straight up clones developed from scratch, not excess inventory / ghost shifts / packaged rejects. I guess it might be a digital/mixed-signal split, with the two worlds having different issues?
(also interestingly the STM32 clones I've seen had stacked die flash because they didn't fab them in a technology that could also do flash, so you can easily tell the counterfeit from sanding down the package and looking for an extra set of bonding wires; it's also a cool place to access the internal flash bus if you wanna bypass some readout protection :) )
Re: How bad can a $2.97 ADC be?
#15> These are cheap, relatively fast, and not particularly good. While they sport impressive-sounding 12- and 16-bit readouts, the effective number of bits (ENOB) is usually around 8 or 9.
I don't think that's quite accurate for reasonably modern MCUs. You can typically shake 10+ bits out of them, but you need to take a lot of precautions, such as providing very stable external reference voltage and shutting down unneeded subsystems of the chip.
They're still not as good as standalone ADCs, but they're at a point where you can actually use them for 90% of things that require an ADC.
In cases where you need more bits, there's a lot more that must go into the design, which is what gives me a pause about the article. There's nothing about the PSU the author is using or how he managed the MCU noise and RFI. So I don't know if the findings here are that these are knock-off devices with worse specs, or if his overhead LED lamp is causing a lot of interference.
Re: How bad can a $2.97 ADC be?
#16Ooh this is interesting! I've seen some big price differences between Digikey and LCSC at small volumes; not sure! You can also sometimes buy direct from TI.
Of interest from early in the article: I'm curious how these external ones compare to onboard, e.g. STM32's. Btw, the TI one listed is actually pretty simple to use in comparison. The ST integrated ones have more config and hardware considerations, e.g. complicated calibration procedures, external VREF (mentioned) etc. So, if you do app the config, is the integrated one as good?
The integrated ones usually have nice ways to integrate with timers and other onboard periphs.
Re: How bad can a $2.97 ADC be?
#17Has there been any updates on ADC technology? What does SKA/CERN use?
Curious too. The part in question has been around for a while.
Re: How bad can a $2.97 ADC be?
#18> So what’s going on with the cheap parts? My best guess is that these are either quite good copies, or failed parts that somehow made their way into the hobbyist supply chain. The vast majority of counterfeit chips I've seen were from ghost shifts but IIRC TI fabs all their analog parts in house, I doubt they're ghost shift parts or failed QC. I think its probably a relabeled ADS1015.
Author here. I did consider this, as others have reported getting ADS1015 marked as ADS1115. If it were an ADS1015 the readout would be truncated at 12 bits. These parts definitely delivered 16 bits of readout.
Re: How bad can a $2.97 ADC be?
#19Earlier quoted context omitted.
TI makes all their analog stuff in house so that's unlikely. That's far more common for fabless companies that send their parts off to an outside fab.
What does TI do with their out-of-tolerance products? Straight in the garbage?
Yes, though depending on the product line it may be binned into lower quality parts first. Remember though, the marginal cost of these chips is so small the packaging is usually more expensive than the silicon. They often get tested before the wafer is even sliced up so any waste is hardly worth mentioning until you get into modern processes with large error rates and huge chips like CPUs.
Re: How bad can a $2.97 ADC be?
#20The price difference could be explained by LCSC purchasing in bulk directly from TI or similar and selling them at lower margins because their volumes are larger. I've seen "clone" chips sold at LCSC, but they're listed under a different brand (I can't recall one off memory unfortunately).
Never had bigger issues ordering from LCSC. And I buy a lot of stuff from them.
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