How to Read Date Codes on ICs/chips

Ever wondered what year that old chip you have laying around was? Are you just simply curious? Here's how to read the date codes on most common ICs/chips.

Everything I have here is based of the (surprisingly little) info I found on the web. If you know something I said wrong, or something to add, by all means, please tell me!

Step 1: Find the Date Code

"Uh..." (Squints at chip) "Lemme see..."

First you need to locate the date code. If it's there, (Some chips just don't seem to have one), it's likely it's a 4 digit code. Usually the 4 digits are by themselves. In the picture, the 4 digits circled in green is the date code.

Step 2: Read Date Code:

So you've found the date code! Hopefully you didn't need a magnifying glass! (Some chips are really hard to read off of...)

The date code usually is in either of two formats: YYWW or WWYY, where WW stands for the week number of the year (Not the month, seems strange, doesn't it?), and where YY stands for the last two digits of the year. For example, in the picture, the date code reads 8332, meaning it was made in the year 1983, in the 32nd week.

As verence helpfully pointed out in the comments, most datasheets will
have info on how to read the date code, as long as you can find a datasheet. ;)

There are a few reasons that chip makers use the week format rather than months, but the main reason is because it narrows the date down even more than a month, to the exact week. That can be useful for tracking batches of bad chips that need to be returned.

Step 3: Finished!

Hopefully this was some help to you!

Unfortunately, however, a lot of chips, (At least many of the ones I have) seem to either not have date codes, or be in a different format I've not found yet. If you know of more formats, please tell me in the comments, so I can add them to this instructable.

Comments

[verence]

Using the week and not the month is not a strange choice. Space on the chips is scarce (okay, not for those old DIP monsters but even then there were smaller chips). Using the month (01..12) you need two digits, but use only an eighth of the possible combination (00..99). By using the week you still need only two digits but use halve of the possible combinations. So your resolution is 4 times better! And the code can be decoded with a standard wall calendar.

If you want to be sure abot the date code, check the manufacturers data sheet for the chip. There is always a paragraph and/or drawing that explains how the chip is coded. But make sure to check the right manufacturer. Different manufacturers may (and do) use different ways to label the same kind of chip.

[Jfieldcap]

Yeah, I did realize that it was more logical to do it that way, for more precision. Thanks for the clear explanation though, and the suggestion on looking at the datasheets! Maybe I should change that to "Seems strange, doesn't it?" and then explain why they do it that way.

[verence]

Ahh, don't read too much into my comment. If you like to change that, go on! If not ... well, for the layman it is kind of strange.

Maybe a good idea to add the advice to look at the specific manufacturer's data sheet, just to round it up.

[Jfieldcap]

I did so. Thank you!

[Kreat0r]

very informative, good job!

[Jfieldcap]

Thanks!

[Leners]

interesting! thanks for sharing!

[Jfieldcap]

Thank you!

[DIY Hacks and How Tos]

That is really interesting. I didn't know that.

[Jfieldcap]

Thanks! I didn't think it was much, but glad to enhance knowledge!