BD139/140 driver

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#23
I think Philips' BD139/140 were discontinued before the name change to NXP already. They used to be repackaged versions of the TO-92 BC639/640, which apparently have now gone the way of the dodo as well (though it appears they still are well-stocked). Looks like only the surface mount versions (BCP/BCX53/56 etc.) are still in production. Thermally those make more sense than TO-92 anyway.
 
#24
sgrossklass said:
I think Philips' BD139/140 were discontinued before the name change to NXP already. They used to be repackaged versions of the TO-92 BC639/640.....
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That is my recollection too. When we look at second sources like On-Semi though, the TO92 version must be a smaller die because Cob is much lower and this makes them quite a different beast if you substitute for the TO126 version. The compensation is affected quite markedly when used in VAS applications and on a couple of designs I used them on, the resulting SQ was very different.

I guess that is the basis for guys quoting their impressions of bass, mids, highs being excellent, good, poor etc. when comparing supposedly equivalent parts - particularly if it means changes that have an impact on compensation.
 
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#25
Yes, non-Philips BD139/140 are somewhat bigger and more rugged devices. fT = 50 MHz @ 100 mA vs. 190 MHz @ 50 mA is quite a price to pay though.

If datasheets are an indication, the Fairchild BD139 does a bit better in beta droop (neither are particularly grand), while the Philips part keeps up beta much better at low Ic. In any case, plenty of evidence that they are rather different parts.

It's not so clear to me how the Fairchild, ST and On Semi variations compare. The last one looks a little better when it comes to keeping beta constant at both ends, and Cob @5V is closer to 16 pF or so (props for giving a graph of Cob and Cib at all!). The ST part has the most pitiful datasheet, on the level of no-name general purpose devices, but I suppose the parts themselves are about on Fairchild level.

Interestingly, ISC claim that their BD139/140 have the fT values of the Philips parts. I'll believe that when someone's gotten hold of some and measured it.
 
#26
Most second-source suppliers only offer basic datasheets but this is another source claiming their Ft is 190 MHz. I believe them on their reputation, though. Well, I just ordered some pairs and will see if I can compare Cob of Unisonic with Fairchild, ST and maybe ICS and On-Semi parts, using my modest instruments. International shipments are slow this time of year, so don't expect this any time soon.
http://www.utc-ic.com/uploadfile/2011/1012/20111012023505473.pdf
 
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