BC337 hfe distribution
in [Design]
|
Prev: Released scope_pic, a digital storage oscillosope in a PIC 18F14K22, as GPL
Next: Multimeter Display Fade
From: E on 9 Apr 2010 17:23 "Jim Thompson" <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> kirjoitti viestiss�:eq3vr51hn9adhsi5dnqtjpsk1i0rktbpfv(a)4ax.com... > Roughly 80K _untested_ die (if wafer is 8"). The wafer is probably > auto-probed and binned into various device numbers. > They have still not managed to get their processes so much under control that they can make what is needed instead of what happens to come out? BC337, BC547, 2N2222 etc. have been around for quite some time... (Google didn't know how long) -ek
From: Sjouke Burry on 9 Apr 2010 17:29 E wrote: > Just measured hfe from some BC337-40 at about 5 mA collector current. > Unfortunately nothing very interesting there > > Results: > Sample size: 960 pcs > minimum hfe: 388 > maximum hfe 513 > (datasheet limits are 250 and 630) > avarage: 452 > avarage deviation: 27 > median: 463 > mode: 477 > Distribution is a bit strange looking with two spikes > Histogram here: http://koti.mbnet.fi/hsahko/hfe/ > > -ek > > That looks awfully like a mix of two production runs......
From: Joel Koltner on 9 Apr 2010 17:42 "E" <invalid(a)invalid.invalid> wrote in message news:hpo5sl$l4o$1(a)news.eternal-september.org... > They have still not managed to get their processes so much under control > that they can > make what is needed instead of what happens to come out? I think it's more a case of, "for the vast majority of applications, what comes out is already good enough." Indeed, it makes no sense to try to tighten up the specs of a 2N2222 since, by the very nature of selecting it for a design, the designer is saying that tolerances can be quite wide and his design is still going to work anyway. And keep in mind that BJTs have a lot less spread in their device parameters than FETs anyway. In the simple hybrid-pi small-signal model of a BJT, no device parameters whatsoever come into play! :-) (...which is not true for FETs...) At the end of the day I imagine it comes down to cost, though -- if it cost next to nothing to trim hFE of a 2N2222 to 1%, it would be happening. (Note that trimming a particular parameter like hFE to 1% *might* imply that you have to trim various parameters in your process far more tightly -- this is what can get expensive...)
From: TTman on 9 Apr 2010 17:47 "Jim Thompson" <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote in message news:eq3vr51hn9adhsi5dnqtjpsk1i0rktbpfv(a)4ax.com... > On Fri, 09 Apr 2010 21:25:45 +0100, John Devereux > <john(a)devereux.me.uk> wrote: > >>"E" <invalid(a)invalid.invalid> writes: >> >>> "Joel Koltner" <zapwireDASHgroups(a)yahoo.com> kirjoitti >>> viestiss�:fmLvn.199280$rq1.66072(a)en-nntp-02.dc1.easynews.com... >>>> "E" <invalid(a)invalid.invalid> wrote in message >>>> news:hpnv2c$5it$1(a)news.eternal-september.org... >>>>> Distribution is a bit strange looking with two spikes >>>> >>>> Maybe two different batches of parts? >>>> >>> >>> Possibly, alltought they were all from same bag. >>> Or maybe just from different wafers? >>> How many BC337 fit one wafer? Probably quite many... >>> >>> -ek >>> >>> >> >>Perhaps they take all the middle ones for a tighter-spec version? > > Roughly 80K _untested_ die (if wafer is 8"). The wafer is probably > auto-probed and binned into various device numbers. > > Discrete device production is so automated... it's fascinating to > watch the automated handling equipment :-) Very true, my brother builds machines that makes the wafers....
From: Tim Williams on 9 Apr 2010 17:55
"E" <invalid(a)invalid.invalid> wrote in message news:hpo5sl$l4o$1(a)news.eternal-september.org... > They have still not managed to get their processes so much under control > that they can > make what is needed instead of what happens to come out? BC337, BC547, > 2N2222 etc. have been > around for quite some time... (Google didn't know how long) First hit for "2N2222 history", a few pages in: http://www.semiconductormuseum.com/Transistors/Motorola/Haenichen/Haenichen_Page7.htm Introduced by Motorola in 1962. Anyone know how much it retailed for that year? With the loose specs on a 2N2222, you'd think a fairly loose run could be binned into all sorts of parts. Maybe they did, once upon a time. 'Course, the 2N2222 spec (and the other three in the series) is so loose as to avoid that, at least initially. I've heard at least one suggestion that modern 2N2222s should be avoided because, due to the lax specifications, modern processes could be dangerously faster than the original, leading to parasitic oscillation where you aren't expecting it. Personally, I use 2N3904 and 2N4401, which have proper spec sheets. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms |