Author Options:

What's the difference between a TIP 31 and a TIP 122? Answered

I am planning to build my first DIY LED Strip panel and the requirement states TIP 31. I can find only TIP 122 close to where I live. Can I use TIP 122 in Place of TIP 31 . I want to use it with an Arduino .




2 years ago

Both are NPN, the TIP31C a 3A 100V and the TIP122 a 5A 100V is a Darlington introduced a year later.

The TIP31C has a poor min gain of 10 and a low forward Vce=1.8V drop , , , while the TIP122 has a superior gain of 1000 but a high forward Vce =4.0V drop and the builtin inverse parallel diode ( good for inductive loads ) making it "a good switch" as Steve pointed out, if you can stand the higher Vce drop, which will manifest as thermal heat that has to be cooled.

Since you plan to use the 122 in place of the 31 you will be only using 3A which drops the Vce to a much more reasonable 2.0V.

So go ahead and double the base resistor value and build with the TIP122 :-)


2 years ago

A TIP 122 is actually better as a switch which I assume is all this is doing.