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Datasheet confusion

R

Rikard Bosnjakovic

Jan 1, 1970
0
I have two datasheets describing the transistor 2N3906. Consider these
pdf-files:

http://www.datasheetarchive.com/datasheet.php?article=3743092
http://www.datasheetarchive.com/datasheet.php?article=3743093

The first one tells me the dissipation (Pd) is 625mW, while the second
tells me Pd is 350mW. I'm aware of the fact that this may be because
two different companies made hem, but are components really allowed
the same brand if their characteristics differ?

I'm asking because I don't have any 2N3906 at home (and I'm not gonna
order new ones) so I'm looking for replacements. But if their values
differ - how am I supposed to know which replacements to look for?
 
P

Phil Allison

Jan 1, 1970
0
"Rikard Bosnjakovic"
I have two datasheets describing the transistor 2N3906.


** No you do not - they are not data sheets.



** Those are second party re-listings.

Likely compiled by 12 year old Mexicans.


The first one tells me the dissipation (Pd) is 625mW, while the second
tells me Pd is 350mW.


** Original manufacturers data sheets for individual types are there if you
bother to look.

Shame YOU are too damn lazy to feed a number into Google.


I'm asking because I don't have any 2N3906 at home (and I'm not gonna
order new ones) so I'm looking for replacements. But if their values
differ - how am I supposed to know which replacements to look for?


** For the same type number in the exact same package - there is no
significant variation in Pd.




....... Phil
 
B

Bob Eld

Jan 1, 1970
0
Rikard Bosnjakovic said:
I have two datasheets describing the transistor 2N3906. Consider these
pdf-files:

http://www.datasheetarchive.com/datasheet.php?article=3743092
http://www.datasheetarchive.com/datasheet.php?article=3743093

The first one tells me the dissipation (Pd) is 625mW, while the second
tells me Pd is 350mW. I'm aware of the fact that this may be because
two different companies made hem, but are components really allowed
the same brand if their characteristics differ?

I'm asking because I don't have any 2N3906 at home (and I'm not gonna
order new ones) so I'm looking for replacements. But if their values
differ - how am I supposed to know which replacements to look for?

The 3906 is a small signal transistor. It is not meant to dissipate any
significant power. If you keep the dissipation below a couple of hundred
milliwatts you should be ok. If you are asking about 650mW, you are using
the WRONG part regardless of what some data sheets may say. Be safe and do
not exceed the lowest listed value regardless of manufacturer. If you need
more power, pick a different part.
 
J

John Popelish

Jan 1, 1970
0
Rikard said:
I have two datasheets describing the transistor 2N3906. Consider these
pdf-files:

http://www.datasheetarchive.com/datasheet.php?article=3743092
http://www.datasheetarchive.com/datasheet.php?article=3743093

The first one tells me the dissipation (Pd) is 625mW, while the second
tells me Pd is 350mW. I'm aware of the fact that this may be because
two different companies made hem, but are components really allowed
the same brand if their characteristics differ?

Neither of those compilations is actually a data sheet.
They are collections of interpretations of the information
from data sheets. The first gives a power limit and the
conditions that apply to that limit (25 C ambient). the
second gives a power limit but no conditions, so it may
apply to a completely different situation, like maximum
rated ambient temperature.

These compilations are handy to find somewhat similarly
rated devices, to start a selection process (for anything
with more at stake than a hobby project), but the final
decision should always include looking at the actual
manufacturer's data sheet, and reading all the fine print.
The same specification often means different things when you
take the notes and specified test conditions into account.

The universe is complicated. Sorry.
 
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