Transistor datasheets - different values for same component? - Page 1
Forum section: electronics / beginners

author: 9voltbrain
author_rank: Contributor
timestamp: July 18, 2022, 07:27:25 pm
content: When googling for the datasheet for the BC547 transistor, I came across two different datasheets, where one said the max collector current was 100mA, whereas the other said 500mA. Which one is correct? Are they referring to different kinds of IC values, different transistor versions, or what is going on here? Power dissipation was different as well.1.https://www.sparkfun.com/datasheets/Components/BC546.pdf2.https://www.farnell.com/datasheets/59764.pdf

author: Benta
author_rank: Super Contributor
timestamp: July 18, 2022, 07:45:46 pm
content: Never go to dodgy pages for data sheets, go directly to the manufacturer page.In this case I'd suggest onsemi.com or Nexperia.com.100 mA is correct, BTW.

author: magic
author_rank: Super Contributor
timestamp: July 18, 2022, 09:20:09 pm
content: That dodgy site is Farnell and they serve an original Fairchild datasheetThe answer is that there was a time when Fairchild rated their version of the transistor for more Ic, but they changed the rating back to the usual 100mA. Chances are that the 500mA Fairchild part wasn't really great at 500mA due to poor β - there are no high current specs in your datasheet. Don't bother looking for unicorns, get BC327/BC337 or 2N2222/2N2907 for more current in TO92 package.

author: Benta
author_rank: Super Contributor
timestamp: July 18, 2022, 09:31:20 pm
content: Quote from: magic on July 18, 2022, 09:20:09 pmExactly. I never trust data sheets on second- or third-hand, but always go to the source. Farnell data sheets are uploaded by students earning a bit of money during their vacation... or by third world very poor people.Your deep trust in Farnell is commendable, but misplaced. A 1997 data sheet for the most common transistor in the world? Really!

author: magic
author_rank: Super Contributor
timestamp: July 18, 2022, 09:39:35 pm
content: Well, I hope that this is not the datasheet they show today on the product's page but an old link that OP got from a search engine.I don't use Farnell, by the way. I'm just saying that datasheets from reputable distributors are generally legit, but they can be outdated, as we saw

author: Zero999
author_rank: Super Contributor
timestamp: July 18, 2022, 09:44:06 pm
content: https://www.onsemi.com/pdf/datasheet/bc546-d.pdf

author: magic
author_rank: Super Contributor
timestamp: July 18, 2022, 10:02:39 pm
content: Or this onehttps://www.onsemi.com/pdf/datasheet/bc550-d.pdfIf you want to know, the former is for Motorola version, mine is for Fairchild version, both owned by ON semi these days. To know which you are buying, look at the letters at the end of the part number.

author: 9voltbrain
author_rank: Contributor
timestamp: July 18, 2022, 10:08:51 pm
content: Quote from: magic on July 18, 2022, 09:20:09 pm2N4401 seems like a good option too, right?https://www.onsemi.com/pdf/datasheet/2n4401-d.pdfQuote from: magic on July 18, 2022, 09:39:35 pmAn online shop I buy stuff from linked to the "dodgy" one. It was funny because for the BC547b they linked to the correct datasheet showing 100mA, and for the BC547c they linked to the one showing 500mA. More gain and more current!Quote from: magic on July 18, 2022, 10:02:39 pmThe ones I bought just say "R1 E" at the end.

author: David Hess
author_rank: Super Contributor
timestamp: July 18, 2022, 10:24:08 pm
content: National made the BC547 on their process 10 which does say up to 500 milliamps. Fairchild inherited National's discrete products, right? So maybe that is where the number came from.Something odd that I noticed is that the BC547, and most of the BC series, is in the old Fairchild selection guide, but missing from their old discrete datasheets.

author: golden_labels
author_rank: Super Contributor
timestamp: July 18, 2022, 10:26:58 pm
content: BC548 and friendson Wikipedia. That should explain why you see the differences and where your expectations should be.While buying, the safest option is to use the datasheet provided for that particular item in seller’s inventory. But in general the best idea is just assume the worst case scenario for the given type, across all manufacturers. With things like 548 or 546 one does not normally stick to a particular producer.

author: free_electron
author_rank: Super Contributor
timestamp: July 18, 2022, 11:33:18 pm
content: datasheets do contain mistakes... the one listing 500m is very old...- always look at the publication date- always get the datasheet from the manufacturer website to avoid outdated stuff- do not use a datasheet from brand ABC for a part from brand XYZ. "but but but . the typenumber ..." yeah , but !

author: David Hess
author_rank: Super Contributor
timestamp: July 18, 2022, 11:48:59 pm
content: Quote from: free_electron on July 18, 2022, 11:33:18 pmI would have said that it was not old enough. That is why I went looking for the older Fairchild datasheet, which apparently never existed even though Fairchild had the BC547 in their selection guides. The old Fairchild apparently made the BC547, and later inherited National's BC547 when Fairchild was reborn.Process 10 is the same as used for the 2N2222, which is consistent with the age of the BC547. Going through the data National published on their various processes might reveal a pattern. Some die shots would not hurt, or run some tests for things like hfe and saturation voltage to find out what is going on.

author: free_electron
author_rank: Super Contributor
timestamp: July 19, 2022, 12:03:13 am
content: BC547 is VERY old. i was using those in 1984 ... possibly before.that being said. the BC547 you buy today (they are still in production) is not the same as it was back then.

author: David Hess
author_rank: Super Contributor
timestamp: July 19, 2022, 12:53:47 am
content: Quote from: free_electron on July 19, 2022, 12:03:13 amThe same goes for the 2N2222. I have seen old 2N2222 dies, and they do *not* match National's process 10 which uses an interdigitated structure. Now that National process is old, but not as old as the process used for the original 2N2222.Does it matter? No, as long as you only rely on the guaranteed specifications, which is usually not a significant problem.Incidentally, die size can be estimated from the specifications for power dissipation, and is often a good way to identify if a new process was used.

author: magic
author_rank: Super Contributor
timestamp: July 19, 2022, 08:28:44 am
content: Quote from: 9voltbrain on July 18, 2022, 10:08:51 pmYep, similar specs to 2N2222.

author: SeanB
author_rank: Super Contributor
timestamp: July 19, 2022, 09:32:30 am
content: Same die actually, like the 2N2219, just a different package, and power dissipation ability.

author: Gyro
author_rank: Super Contributor
timestamp: July 19, 2022, 10:40:30 am
content: Looking at the two datasheets, somebody at Fairchild screwed up and it got through their document 'review' process. On the 1997 datasheet it is supposed to read Absolute maximum 'Pc CollectorPower Dissipation500mW'. The later datasheet includes both figures - Ic (100mA) and Pc.Shame on Farnell for just grabbing some random old datasheet off the web. Their datasheet should match the product they are selling, which definitely won't be Fairchild (unless their stock rotation is really bad).

author: David Hess
author_rank: Super Contributor
timestamp: July 19, 2022, 06:55:09 pm
content: Quote from: Gyro on July 19, 2022, 10:40:30 amI recall deciding the same thing when I first ran across that, however I just found a similar Fairchild 2N2222 datasheet which lists a 1 amp maximum collector current, and there is no place where that could have come from a 1W specification.

author: wraper
author_rank: Unknown
timestamp: July 19, 2022, 07:15:09 pm
content: Quote from: Gyro on July 19, 2022, 10:40:30 amFarnell has newer fairchild/onsemi datasheets for parts it still sells, OP probably just googled a link to old datasheet still hosted by farnell.

author: Benta
author_rank: Super Contributor
timestamp: July 19, 2022, 07:23:46 pm
content: Quote from: wraper on July 19, 2022, 07:15:09 pmThat's beside the point. Distributor do not have ownership of the data sheets, the manufacturers do.That's why you always go to the source, not to the messenger.