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Voltage polarity on transistor data sheets

Hi,

I seem to get stuck on the stupidest things.

I've been reading the datasheets for two transistors, the MPSA55 and
the KSP55, and I'm curious if the polarity differences for collector
current, collector-base voltage, etc are important, because the two
transistors are "cross-referenced" on quite a few sites. The data
sheets for the transistors are located at:

http://www.fairchildsemi.com/ds/MP/MPSA55.pdf
http://www.fairchildsemi.com/ds/KS/KSP55.pdf

So for example, on the MPSA55's datasheet, Vcbo is +60V, and on the
KSP55's datasheet, Vcbo is -60V. I would like to know if the sign
difference is significant here.

I assure you that I have no intention of using these transistors any
time soon, because I know very little about them. However, they could
be useful at some point in the future, and I am trying to save myself
$6.50 from digikey by ordering them with some other stuff. So this is
officially a six dollar question. =)

Thank you very much for your help.
 
R

Ralph Mowery

Jan 1, 1970
0
Hi,

I seem to get stuck on the stupidest things.

I've been reading the datasheets for two transistors, the MPSA55 and
the KSP55, and I'm curious if the polarity differences for collector
current, collector-base voltage, etc are important, because the two
transistors are "cross-referenced" on quite a few sites. The data
sheets for the transistors are located at:

http://www.fairchildsemi.com/ds/MP/MPSA55.pdf
http://www.fairchildsemi.com/ds/KS/KSP55.pdf

So for example, on the MPSA55's datasheet, Vcbo is +60V, and on the
KSP55's datasheet, Vcbo is -60V. I would like to know if the sign
difference is significant here.
As both sheets specify them as a PNP transistor, the - sign does not mean
anything significant in this case. All one sheet is doing is to put in
the - sign to denote the collector is negative inrespect to the emitter for
a PNP transistor. Some sheets will put in the - sign for this reason but
some will not and expect you to know to hook the collector to the negative
side of the power supply in respect to the emitter.
 
R

Rich Grise

Jan 1, 1970
0
As both sheets specify them as a PNP transistor, the - sign does not mean
anything significant in this case. All one sheet is doing is to put in
the - sign to denote the collector is negative inrespect to the emitter for
a PNP transistor. Some sheets will put in the - sign for this reason but
some will not and expect you to know to hook the collector to the negative
side of the power supply in respect to the emitter.

Actually, longjohnstuartmill misread teh a55 data sheet - it doesn't say
+60, it just says 60, so it's OK. :)

Cheers!
Rich
 
Ralph said:
As both sheets specify them as a PNP transistor, the - sign does not mean
anything significant in this case. All one sheet is doing is to put in
the - sign to denote the collector is negative inrespect to the emitter for
a PNP transistor. Some sheets will put in the - sign for this reason but
some will not and expect you to know to hook the collector to the negative
side of the power supply in respect to the emitter.

Thanks. That's useful information. =) I never saw it explicitly
stated anywhere. Maybe that's because everybody knows it
automatically...

Heh, my questions are so simple that they're borderline trollish. I
think it's partly because I don't know anybody that I could ask in
person, and also because I'm trying to learn using only web sites, some
old library books (and when I say old I mean they use vacuum tubes),
and this newsgroup. But it could also be because I'm not too bright.

Oh well... Eventually I'll either give up or save enough money to take
some courses.

Thanks again for your help.
 
R

Ralph Mowery

Jan 1, 1970
0
Thanks. That's useful information. =) I never saw it explicitly
stated anywhere. Maybe that's because everybody knows it
automatically...

Heh, my questions are so simple that they're borderline trollish. I
think it's partly because I don't know anybody that I could ask in
person, and also because I'm trying to learn using only web sites, some
old library books (and when I say old I mean they use vacuum tubes),
and this newsgroup. But it could also be because I'm not too bright.

There are lots of things that are done in electronic circuits that the
writers are expecting you to know. For example tube filiments are not
always shown in the schematics or most likely they are not shown with the
other tube elements but you are expected to find them on the schematic
grouped with all the filiments connected to the transformer. Same with some
ICs . The ones that use a positive and negative voltage may or may not show
the power supply leads. Then they may be grouped together and a bunch of
capacitors shown with them. You are suspose to know to put the capacitors
close to the power pins of each IC.

I had worked with electronic schematics for years and then took a job where
I also had to look at electrical blueprints. It took a while before I could
follow the simple prints due to the same problem. Just had to learn what I
was suspose to know :)
 
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