# Online database of data sheets that isn't horrible?

When wanting to look up a datasheet for a random part number I encounter in a circuit, say an AD9862, my first action is just to type it into google. For about half of the parts I encounter, particularly ones made by big respected brand names (like the Analog Devices example I used above) this gives me as a first hit the official manufacturer page and datasheet. Happy.

But about half of the time, especially with commodity/generic parts, say a 7812, the top hits are all these garbage sites like alldatasheet, getdatasheet, or datasheetcatalog dot com (I'm not typing out their URLs, since I don't want to further increase the pagerank of these junk websites). These websites are ugly, crammed to the brim with ads, with bad search capabilities, lots of SEO to get them highly ranked by google, but often with very little in the way of useful content.

Do you have a favorite way to find datasheets online, that sidesteps these middle-man ad-crammed sites? Is there a nice, user-curated perhaps, clean, low-ad-content database of datasheets out there somewhere?

• For one thing, use the Optimize Google extension to filter out the sites you don't want in your search results. – endolith May 12 '11 at 5:22
• Also, don't forget AdBlock Plus, don't see any ads on those sites ;). – Thomas O May 12 '11 at 6:45

The others have made great recommendations. I'll add one small google hack that I use a lot:

[part number] datasheet filetype:pdf

So let's say you're looking for the LM629 datasheet... you'll google

LM629 datasheet filetype:pdf


or maybe an 74LS04:

74LS04 datasheet filetype:pdf


This has always worked well for me, since I know that the datasheets are going to be in the PDF format.

• There is one of those sites that will serve bogus results with a pdf mime type, just to spam the results you are getting. But Google works well enough that the spam results won't be on the first page of results. – markrages May 12 '11 at 3:01
• +1 for googlehacks. Also very (!) helpful in google: add the phrase site:manufacturer.com, for example: 74LS04 datasheet filetype:pdf site:nxp.com – zebonaut May 12 '11 at 5:14
• @zebonaut: that's another useful one for sure, though I tend to not use it for datasheets. – Dave May 12 '11 at 5:16

I only get datasheets from the original manufacturer, and avoid all third-party datasheet sites. With the manufacturer, you know that you're getting the latest, most up to date info. I've been doing this long enough where I can locate the original manufacturer within a minute or two. And places like Digikey will list the manufacturer and mfg part number so it's fairly painless.

For commodity parts, most of them are from National, TI, or On Semi so even then I can locate the original manufacture quickly. Now that National was bought by TI, this will get even quicker.

I also have another rule: Don't use parts that I don't know the manufactures part number for. That's the only way to know for sure what you're buying/using. Anything else is too unreliable of a source to trust building an expensive PCB with.

All of this works quite well, unless I'm trying to find a datasheet for an obsolete part or an oddball part. In that case, Google it and search through all the hits. But this only happens when I'm desperate anyway so a little Googling isn't the end of the world.

My favorite method is to use supplier catalogues. Granted I'm not working with many old parts so everything I'm interested in is still in their databases.

Digikey will link directly to the manufacturers datasheet (PDF) in almost all cases. And their search features are much more useful than pure googling in a specific subject matter.

• Digikey and Mouser rule! – Jason S May 12 '11 at 13:09
• +1: online supplier catalogs are great. In addition to linking directly to the datasheet, they often also let you compare and contrast similar parts. They also help you avoid designing-in the "perfect part" that is surprisingly expensive -- or worse, simply unobtainable. – davidcary Feb 12 '12 at 16:49

My favorite is alldatasheet.com because:

• they don't list parts they don't have datasheets for

• they don't tease you and then try to charge for access (the expert-sexchange.com business model)

• they let you actually download the pdf so you can Spotlight it next time and avoid the web entirely.

I think there will never be a great quality site for this because reproducing datasheets is kinda shady. Although most manufacturers don't seem to mind, I believe most of these datasheets are scanned and redistributed in violation of copyright. Although, I guess you could do extremely targeted advertisement. "Looking at voltage regulators? Click for a sample of our new XYZ regulator!"

• +1 because for old parts, they are a good source (and way better than other data sheet archives and whatnot). They also give hints about second source manufacturers. For current products, the manufacturer is the place to get reliable information at. – zebonaut May 12 '11 at 5:13