0
\$\begingroup\$

If you look at the datasheet for the popular WS2811 chip made by World Semi, there seems to be two versions, yet with no associated date stamps or version numbers (only one says version 1.4). The version that seems to be older can be found here, and it indicates the timing to send one bit of data is a total of 1.25 microseconds (usec) in high-speed mode. However, the datasheet that seems to be newer can be found here, and it indicates the timing to send one bit of data is variable, depending on whether you send a 0 or a 1. So, sending a 0 can be performed in 1.1 usec, while sending a 1 can be performed in 1.6 usec. To make things worse, the silent time after the data that causes the chip to latch is also different between the chips: the older seems to indicate 50 usec and the newer seems to indicate 280 usec.

Simply put, these two datasheets can't honestly be talking about the same chip, can they? They both say WS2811, but I feel like the chip's specifications are different enough that you may need to change how you interface with it. Is a manufacturer allowed to change the function of a chip and still keep it named the same? Are there other examples of a manufacturer changing something major but keeping the name the same?

\$\endgroup\$
3
  • \$\begingroup\$ Most datasheets will have some version of this blurb in them: "<manufacturer> reserves the right to change the circuitry and specifications without notice at any time." And that's for a major manufacturer for "important" chips. World Semi's LED drivers are probably less critical. \$\endgroup\$
    – vir
    Commented Nov 2, 2021 at 18:39
  • \$\begingroup\$ I'm not interested in reading the details between these links because my browser is warning me. My apologies for that. But I can say that a good supplier of ICs, such as Microchip, will provide information on "steppings." For example, go to this web site: PIC16F877 docs. There, under Documentation there is a drop-down. Select "Errata" from it and it will show you the docs regarding the steppings for this part. There will be differences there, fairly well-documented. \$\endgroup\$
    – jonk
    Commented Nov 2, 2021 at 18:43
  • \$\begingroup\$ What would not allow manufacturer to do this? Manufacturers can do whatever they like and we don't have to like it. Most likely big customers that buy in millions got info beforehand about changes. The chips may get made at updated process or at different factory or manufacturer and thus there will be difference compared to earlier products, the change may not be intentionally made. \$\endgroup\$
    – Justme
    Commented Nov 2, 2021 at 19:19

1 Answer 1

3
\$\begingroup\$

Here is part of the datasheet from the actual manufacturer's web page:

enter image description here

Which seems to indicate there are at least 5 versions of the datasheet, with important-looking changes. There is also a WS2811M that seems to have the same title on the datasheet.

Not every manufacturer maintains their legacy datasheets online, so you may have to go look at the kind of link you supplied, but generally you want to go to the horse's mouth for the information on current production units.

\$\endgroup\$
2
  • \$\begingroup\$ Ah, that is very helpful, thank you. Now I see it at the bottom of the newer datasheet, but I didn't notice it at first because it's at the end. \$\endgroup\$ Commented Nov 2, 2021 at 19:23
  • 2
    \$\begingroup\$ @user3629081 Don't forget to up-vote and accept questions if they're helpful/useful to you. (That's how thanks is given on this site.) \$\endgroup\$
    – JYelton
    Commented Nov 2, 2021 at 20:07

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.