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If I'm sharing a circuit for educational purposes, I want to make sure that my parts are common generics. I'd much rather specify "2N3904" than "ON Semiconductor MMBT3904". But not all 2N3904s are created equal.

To use an even simpler part, the 1N4148 diode, the ON Semiconductor datasheet specifies IFSM at 1μS to be 4A. However, the Vishay and Diodes Inc datasheets specify 2A.

Suppose I design a circuit that does have a big inrush that rapidly drops (for instance, charging a capacitor). If I look at the ON Semiconductor sheet, I think that it can handle 4A, so I calculate accordingly. Then, I write "1N4148" on my schematic, post the design to the web, and move on. Somebody reads my article, pulls a Vishay diode, and tries to build my circuit, only to see the magic smoke escape their diode.

If I'd read the JEDEC-registered datasheet for the 1N4148, then I wouldn't have this problem. I'd know the ratings that every 1N4148 must meet, and could design around that.

If you think the IFSM example is farfetched and want a different one, note that the VRRM is 100V for the ON Semiconductor and Vishay diodes, but only 75V for Diodes Inc. Or just try to find a 2N2222 datasheet at all (i.e., one without a trailing A, leading P, etc).

However, I haven't found an archive of the JEDEC datasheets for jellybean parts like this. Does anybody know how I can get this information?

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As mentioned by Whit3rd in the answer of What is actually a standard part?, JEDEC manages a list of device registrations of electronic components. For example, 1N400X diodes were originally developed by Motorola, but registered at JEDEC as a generic part number, and its specification is published in ELECTRON DEVICE TYPE REGISTRATION RELEASE NO. 4190C (FINAL).

Unfortunately, the information is not published at the official website of JEDEC, and is only accessible via third-party vendors with payment, thus it's difficult for the general public to learn anything at all from them - a too common problem in many industrial alliances!

But I recently found a shortcut. It only occasionally works, but it does sometimes provide you some of the information in JEDEC specs without payment, it's not satisfactory at all, but better than none, I guess. The secret is: some manufacturers occasionally cite the original JEDEC specs in their own datasheets. For example, using 1N400X diodes as an example, if we take a look at ON Semiconductor's datasheet, we see a small footnote:

† Indicates JEDEC Registered Data

And if we review the datasheet again, looking for the "cross" symbol...

Maximum Ratings

So, in this table, all the data listed in Peak Repetitive Reverse Voltage, Non−Repetitive Peak Reverse Voltage, RMS Reverse Voltage, Average Rectified Forward Current, and Non−Repetitive Peak Surge Current came from the original JEDEC specs of the 1N400X diodes.

There in an additional table with this symbol as well...

Electrical Characteristics

So we can assume that everything listed in Electrical Characteristics is data from the original JEDEC spec as well. But be careful here: all the parameters listed here are maximum ratings, thus only the MAXIMUM values given here are valid JEDEC specs, not TYPICAL values. To verify this fact, I paid to get the original JEDEC spec and crosschecked it.

In conclusion, this method suffers severe limitations: you can only occasionally found them in datasheets of various vendors, you cannot access the primary source and never verify the data is correct, and you must ensure the part number offered by the vendor is identical to the JEDEC part number and not to be confused it with a myriad variations and modifications of the original part.

But it does prove that JEDEC specs, in fact, exist. And it allows you to access some numbers without payment. I guess you can even cross-verify the datasheets from different vendors for hunting.

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Using datasheets from the original manufacturer is essential because the manufacturer (hopefully, most of them do) tested the parts and guarantees the performance to some level. And no, the specs are not all the same.

Find the power that's being dissipated in the part (on paper, but preferably in a spice simulator) then look in the datasheet and see what the package can take (like an SOT-23 is like ~250mW). Also calculate the temperature the part will reach using the junction temperature and the power being dissipated in the part. The temperature should not exceed the maximum rated operating temperature.

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