983Views8Replies

Author Options:

Are the TIP31 and TIP31B or C interchangable? Answered

I  want to make a version of https://www.instructables.com/id/LED-Music-Sync-Headphones/ but I have found three types of the TIB31.  A B and C.  Are they interchangable?

8 Replies

user
advancedMischief (author)lemonie2010-07-05

I like http://octopart.com for finding datasheets.  It usually comes up with better results that Google and it's a lot cleaner that most datasheet specific sites.

Select as Best AnswerUndo Best Answer

user
lemonie (author)advancedMischief2010-07-06


I'll try to remember that.

L

Select as Best AnswerUndo Best Answer

user
finfan7 (author)lemonie2010-07-05

Thanks Lem, that is a massively useful tip.

Select as Best AnswerUndo Best Answer

user
lemonie (author)finfan72010-07-05


It works for most things (silicon), but it's a sod when it doesn't....

L

Select as Best AnswerUndo Best Answer

user
advancedMischief (author)2010-07-05

They are pin compatible. The A, B, C, designation indicate different collector-base and collector-emitter voltage ratings. The plain TIP31 version is rated to 40V and they go up from there, so you can choose the least expensive one. Wikipedia is useful if you want to know more: http://en.wikipedia.org/wiki/TIP31

Select as Best AnswerUndo Best Answer

user
finfan7 (author)advancedMischief2010-07-05

I knew that the only difference was their maximums but I was wondering if they differ in their functions at the low end of their capacities. i.e. does the 80 (B) have a much larger minimum value than the 40? I am working with very small voltages compared to those maximums and I have seen issues where the minimums were not obvious but ended up being too great. Sorry about being vague on the actual question.

Select as Best AnswerUndo Best Answer

user
advancedMischief (author)finfan72010-07-05

Looking at the datasheet  I don't see any indication of the different parts behaving diffrently at the low end of the operating range, so if one version works any of the others should also work.  The only thing you'd have to worry about is the turn-on voltage which I don't see listed, but is usually around 0.6V or 0.7V.  If your just powering a few LED from 3.3V the TIP31 might be overkill.  In that case you can probably get away with using a smaller transistor like the 2N2222 or similar.

Select as Best AnswerUndo Best Answer