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Electronics Forum / Basics / February 2007Datasheet confusion
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?  SignatureRikard. "Rikard Bosnjakovic" >I have two datasheets describing the transistor 2N3906. ** No you do not - they are not data sheets. > Consider these pdf-files: > > http://www.datasheetarchive.com/datasheet.php?article=3743092 > http://www.datasheetarchive.com/datasheet.php?article=3743093 ** 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 > I have two datasheets describing the transistor 2N3906. Consider these > pdf-files: [quoted text clipped - 13 lines] > -- > Rikard. 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. > I have two datasheets describing the transistor 2N3906. Consider these > pdf-files: [quoted text clipped - 6 lines] > 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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