From: RussellMc <apptechnz@gmail.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
CC: ApptechNZ <apptechnz@gmail.com>
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Date: Mon, 27 Jul 2020 05:05:15 -0700
Subject: Re: [EE]:: Your DS18B20 temperature sensor is likely a fake,
	counterfeit, clone...
Thread-Topic: [EE]:: Your DS18B20 temperature sensor is likely a fake,
	counterfeit, clone...
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  BCCs - interest only.

On Sun, 26 Jul 2020 at 02:25, Neil <picdude3@narwani.org> wrote:

> I'd be surprised if anyone on here is surprised by this.
> I've always just "known"/accepted that an expensive part from an
> American company coming from the far east at maybe 1/10th the price
> couldn't be real.  I expected it would be very inaccurate, but not
> surprised about the functional issues they mentioned.
>
> I was not 'shock horror'ing but rather noting due to the well documented
specifics  rather than the often alleged "made at midnight and weekend" and
out of spec partgs and.
In this case the part numbers tell you what MAY be real and what isn't.

The following is very specifically *not* trying to make any point, to prove
or disprove anything or to say anyone or anything is right or wrong or
whatever. It just comes under interesting/whatever/I wonder?

To add to the interest in this case - LCSC is a top end in-China
distributor that tends to be reliable and reputable. They don't say that
you MIGHT NOT get fakes / clones / ... through them but do say that if you
do then they will refund your $ (assuming you notice :-)).
While that may be what you hope is the case from any vendor, it's better
than you may otherwise get in China.
[I have never yet bought from LCSC. I hope to.]

Longish ago I had a (Chinese) manufacturer (of LEDs) who had upmarket test
equipment, and who provided my client with faked burn in test results, and
when my test results did not match theirs they suggested to him that mine
were in error. He managed to believe the correct claims :-).

LCSC sell 7  versions of the DS18B20  - $ -
https://lcsc.com/search?q=3Dds18b20
4 branded Maxim
3 branded UMW (Youtal Semiconductor limited)

The UMW versions are probably type B1 in his writeup.

In 1000 quantity prices are
Maxim   0.89  1.07  1.37  1.43
UMW     0.50  0.55  0.49

In 1000's Digikey charge $2.46 to $2.65 for DS18B20

[FWIW: I consider it entirely reasonable for Digikey to charge higher
prices for a range of reasons. I am not intending any comment on pricing
(or much else)].

I have met numerous Chinese datasheets which have been copied with varying
degrees of modification - sometimes over several manufacturers serially. It
is often possible to trace the source.

UMW provides a separate datasheet for each of their parts (in Chinese).
Page count similar to that of an Intel part.

At a quick skim - the Intel and UMW datasheets are substantially different.
Certainly not an obvious cut and paste - even allowing for translation.
Diagrams, tables, charts ... differ.
Locations of information differ.

In the original article (which I skimmed+) they mentioned lack of eprom in
the clone parts they had met.
The UMW parts have extensive notes on EEPROM / Scratchpad control.

SO - ARE the UMW parts as good / in their spec / up to Maxim spec /
authorised / ...?
His B1 part writeup probably covers this.

Digikey $ -
https://www.digikey.com/products/en/sensors-transducers/temperature-sensors=
-analog-and-digital-output/518/page/1?k=3Dds18b20&quantity=3D1000&ColumnSor=
t=3D1000011&pkeyword=3Dds18b20

UMW datasheets via LCSC
Not compared

https://datasheet.lcsc.com/szlcsc/1912111437_UMW-Youtai-Semiconductor-Co-Lt=
d-DS18B20_C376006.pdf

https://datasheet.lcsc.com/szlcsc/2007032017_UMW-Youtai-Semiconductor-Co-Lt=
d-DS18B20Z_C695837.pdf


https://datasheet.lcsc.com/szlcsc/2007032017_UMW-Youtai-Semiconductor-Co-Lt=
d-DS18B20U_C695836.pdf


Sample Maxim datasheet via LCSC -
https://datasheet.lcsc.com/szlcsc/1810111812_Maxim-Integrated-DS18B20_C9753=
..pdf





       Russell

_________________________________________

n 7/25/2020 8:19 AM, RussellMc wrote:
> https://github.com/cpetrich/counterfeit_DS18B20
>
> ... unless you bought the chips directly from Maxim Integrated
> <https://www.maximintegrated.com/en/products/sensors/DS18B20.html> (or
> Dallas Semiconductor in the old days), an authorized distributor
> <
https://www.maximintegrated.com/en/aboutus/contact-us/distributor-offices.h=
tml
>
> (DigiKey,
> RS, Farnell, Mouser, etc.), or a big retailer, or you took exceptionally
> good care purchasing waterproofed DS18B20 probes. We bought over 1000
> "waterproof" probes or bare chips from more than 70 different vendors on
> ebay, AliExpress, and online stores -big and small- in 2019. All of the
> probes bought on ebay and AliExpress contained counterfeit DS18B20
sensors,
> and almost all sensors bought on those two sites were counterfeit.
>
> Author: Chris Petrich, 25 July 2020. License: CC BY. Source:
> https://github.com/cpetrich/counterfeit_DS18B20/
>
> (Sensor information based on sensors or probes ordered well into 2020
> rather than in or around 2019 are marked "*(2020)*".)
--=20
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