BC337 hfe distribution
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From: legg on 10 Apr 2010 19:06 On Sat, 10 Apr 2010 21:15:09 +0300, "E" <invalid(a)invalid.invalid> wrote: >"legg" <legg(a)nospam.magma.ca> kirjoitti >viestiss�:u381s55up8gpbbc8t30ka4g4spc0lkcv5v(a)4ax.com... > >>>-ek >>> >> BC337-40 is a binned-by-hfe part number, so you can't expext a >> 'natural' hfe distribution curve. >> >Yes, it is hfe binned part. Unfortunately I don't have many non-hfe >binned transistors, but found some MPSA42 high voltage bipolars. >hfe distribution is actually pretty similar in those than in bc337. >Min-max:118-142, relative avarage deviation: 2.6% > >Maybe I need to buy some more of them to get some idea about >batch-to-batch variation > For applications requiring gain spreads that are narrower than those offered by the vendor, you already seem well situated to address the issue, by direct measurement. Before accepting hfe as a critical design parameter, you'd best examine effects on measurement method-induced and general environmental effects on this feature, reversible or otherwise. This information may be more economically obtained from a good reference library, or even a simple google search...... RL
From: Jim Thompson on 10 Apr 2010 20:01 On Sat, 10 Apr 2010 18:06:53 -0500, legg <legg(a)nospam.magma.ca> wrote: >On Sat, 10 Apr 2010 21:15:09 +0300, "E" <invalid(a)invalid.invalid> >wrote: > >>"legg" <legg(a)nospam.magma.ca> kirjoitti >>viestiss�:u381s55up8gpbbc8t30ka4g4spc0lkcv5v(a)4ax.com... >> >>>>-ek >>>> >>> BC337-40 is a binned-by-hfe part number, so you can't expext a >>> 'natural' hfe distribution curve. >>> >>Yes, it is hfe binned part. Unfortunately I don't have many non-hfe >>binned transistors, but found some MPSA42 high voltage bipolars. >>hfe distribution is actually pretty similar in those than in bc337. >>Min-max:118-142, relative avarage deviation: 2.6% >> >>Maybe I need to buy some more of them to get some idea about >>batch-to-batch variation >> > >For applications requiring gain spreads that are narrower than those >offered by the vendor, you already seem well situated to address the >issue, by direct measurement. > >Before accepting hfe as a critical design parameter, you'd best >examine effects on measurement method-induced and general >environmental effects on this feature, reversible or otherwise. > >This information may be more economically obtained from a good >reference library, or even a simple google search...... > >RL He who designs by hfe, shall die by hfe :-) Designing by symmetry, I don't ever fret over hfe until I get down near the unity range ;-) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy
From: Robert Latest on 11 Apr 2010 07:22 legg wrote: > For applications requiring gain spreads that are narrower than those > offered by the vendor, you already seem well situated to address the > issue, by direct measurement. > > Before accepting hfe as a critical design parameter, you'd best > examine effects on measurement method-induced and general > environmental effects on this feature, reversible or otherwise. Also don't forget that certain parameters may shift over the lifetime of the part while staying in spec. An extremely unwanted property of electronic devices but sometimes hard to get rid of. robert
From: whit3rd on 11 Apr 2010 17:10 On Apr 11, 4:22 am, Robert Latest <boblat...(a)yahoo.com> wrote: > legg wrote: > > For applications requiring gain spreads that are narrower than those > > offered by the vendor, you already seem well situated to address the > > issue, by direct measurement. > Also don't forget that certain parameters may shift over the lifetime of > the part while staying in spec. If it matters, hfe rises with temperature AND with aging; Vce falls with age. It's not certain that 'staying in spec' is gonna happen, you know, that's what the 'lifetime of the part' phrase is intended to warn of. Excellently careful wording, Bob; you could teach to marketers. :-)
From: Fred Bartoli on 14 Apr 2010 07:18
whit3rd a �crit : > On Apr 11, 4:22 am, Robert Latest <boblat...(a)yahoo.com> wrote: >> legg wrote: >>> For applications requiring gain spreads that are narrower than those >>> offered by the vendor, you already seem well situated to address the >>> issue, by direct measurement. > >> Also don't forget that certain parameters may shift over the lifetime of >> the part while staying in spec. > > If it matters, hfe rises with temperature AND with aging; Hfe with aging? What's the mechanism? > Vce falls with age. Same Q... Google didn't help... -- Thanks, Fred. |