You’ve probably come across this before – you have a poorly documented circuit board and want to know the part number for a tiny SMD chip. Retro computer enthusiast [JohnK] tweeted recently on such a database he recently found, titled The Ultimate Database of SMD Marking Codes. This database is only a few years old judging by the Wayback Machine, but appears to be quite comprehensive and can be found referenced in many electronic forums.
Unlike their larger SMD siblings, these chips in question are so small that there is no room to print the full part number on the device. Instead, common practice is for manufacturers to use a short code of just a few characters. These codes are only unique to each part or package and are not necessarily unique across an entire product line. And just because it’s common practice doesn’t mean the marking codes themselves follow any standard. This seemingly mishmash system works perfectly for the development, procurement, and manufacturing phases of a product’s lifecycle. It is during the phases of repair, refurbishment or simply hacking for fun that these codes can leave you perplexed.
Several sites like this [JohnK] found have been around for years, and adding another database to your toolbox is a good thing. But none of them will ever be exhaustive. There is a good reason for this: maintaining such a database would be a Herculean task. Simply finding the part marking information for a known chip can be difficult. Some manufacturers state this clearly in the datasheet, and some refer you to other documentation which may or may not be readily available. And some manufacturers ask you to contact them for this information, probably because it’s dynamic changes from time to time.
As a quick example of the pitfalls encountered when using these reverse lookup databases, consider two small form-factor SMD parts of a Tiny FPGA module that sits on my desk. Using the database that [JohnK] posted the WXS is most likely a 3.2V LDO from Richtek, part number RT9013-31GB. Corn WXS is also the code for a 3-pin PNP transistor. Richtek itself says the RT9013 should be branded WX=but this is based on a 2009 document. Richtek is one of the companies that says to contact them for the latest marking codes, so this may have changed in the last ten years.
The other chip marked 654 is more than likely a linear voltage regulator, such as the Micrel MIC5365-1.2YCV5. Here’s a situation, presumably coincidentally, where multiple manufacturers use the same code to represent different types of chips – interestingly, all of them are power circuits. Apart from the Micrel part, the others all generate 5.4 VDC. For an FPGA board that probably uses 1.2V, it’s reasonable to exclude those others. As you can see, knowing the package details and guessing the basic function of the chip can help narrow things down. Even if these searches aren’t perfect, finding a match in the database and considering other things you know about the chip means you can usually find the information you want.
In the future, will we have a web-crawling AI that automatically generates and maintains such a database, even calling manufacturers for codes that are not published online? What is your favorite site to look up these codes? Let us know in the comments below. Thanks to [J. Peterson] for bringing this to our attention via the advice line.