Hi:

I am trying to find darlington power transistors (npn/pnp complementary)
in the order of say 5 watts for experimental purposes. I would like the
spice models for the same. I am about to study the class AB amplifier
configuration. Anyone have suggestions?

Thanks,

RS

 

The primary specifications for power transistors are collector-emitter voltage and collector current. Wattage is more of a package spec, although some transistors are fundamentally beefier than others. Start with what you think your worst-case peak output current will be, and double that. Do the same for the circuit operating voltage. With those two numbers, you can go fishing on distributor websites.

A good place to start is the TIP series of parts originally from Texas Instruments. Several of the parts in the 100 series should work for you. Motorola has MJ series parts that are specially designed for audio applications, but the TI parts are much more common.

Digi-Key has 62 different models in stock, but some have large minimum purchase quantity requirements.

https://www.digikey.com/en/products...JkQgUkcQFcCxMiDrd5ikGsjl+E3t0JHoIG5DB8nYGjRNA

ak

 

That amplifier has zero voltage gain. For an amp with gain, R2 is an NPN transistor and R1 is the collector resistor of a gain stage.

 

I see no schematic here of a class AB amplifier with darlington output transistors.
The datasheets for the TIP110 and TIP115 can heat with a maximum of about 40W each with a good heatsink.

You want a signal output power of 5W in each darlington transistor driving an 8 ohms load? Then each darlington will heat with about 4W for a total power of 9 W for each darlington. fasten each darlington to a 5W heatsink.

An amplifier that produces 10W onto 8 ohms has an output voltage swing of 9V RMS which is 25.5V peak-to-peak.
Darlington output transistors will produce a peak voltage loss of about 3V each then the power supply should be 32V.
Each darlington will have a peak voltage swing of 12.75V which produces 1.6A into an 8 ohm speaker. The TIP110 and TIP115 darlingtons are rated for 60v and 2A so they will be fine in this 10W amplifier.

 

 

That amplifier

Which amplifier - ?

ak

 

Which amplifier - ?

ak

The one that was posted, then apparently deleted. Should have quoted it.

 

OnSemi is a good place for audio transistors
https://www.onsemi.com/products/dis...1ZX4yfiF+TGFzdCBTaGlwbWVudHN+IX5PYnNvbGV0ZX4=
they all have SPICE models available.

 

View attachment 302262

Thanks Dennis

 

OnSemi is a good place for audio transistors
https://www.onsemi.com/products/dis...1ZX4yfiF+TGFzdCBTaGlwbWVudHN+IX5PYnNvbGV0ZX4=
they all have SPICE models available.

Thanks Ian. I downloaded some .LIB files from that site. Where might I find some instructions on
which folder to place these files in and how to implement them in Spice? Also, do I need to find a
file with appropriate symbols for these?

Thanks
RS

 

If you are using LTspice, its Help has a section on importing third-party models.

 

If you are using LTspice, its Help has a section on importing third-party models.

Thanks Alec. Where would I find the darlington npn and pnp symbols?
RS

 

Try a bit of googling for 'Darlington spice models'. LTspice accepts some Pspice models too. If the model files you find don't include symbol files (.asy) you can get LTspice to create them using the 'Hierarchy/Create a new symbol' tool. You can then modify the symbols to your liking with the Symbol editor.

 

Try a bit of googling for 'Darlington spice models'. LTspice accepts some Pspice models too. If the model files you find don't include symbol files (.asy) you can get LTspice to create them using the 'Hierarchy/Create a new symbol' tool. You can then modify the symbols to your liking with the Symbol editor.

I have been googling for hours and there is nothing useful. I already tried the autogenerate function
it created a useless symbol and proceeded to tell me that there were missing nodes. Again, useless. I am
sure there is someone out there that has working Spice models for TIP110, TIP115, TIP120 and
TIP125 darlingtons.

 

I have been googling for hours with zero results. I also used the autocreate facility and it created a useless symbol with an error message indicating that there are missing nodes. I am sure that there are people on this site that have TIP110, TIP115, TIP120
and TIP125 spice models that work.

Alex, @Bordodynov probably has something you can use:
http://bordodynov.ltwiki.org/

Turns out I have something you might be able to use. I have generic symbols and specific examples for the TIP121 and TIP127. I've added the NPN and PNP libraries from @Bordodynov so you can adapt things to your needs. I make no representation for the efficacy of these models.

 

Alex, @Bordodynov probably has something you can use:
http://bordodynov.ltwiki.org/

Turns out I have something you might be able to use. I have generic symbols and specific examples for the TIP121 and TIP127. I've added the NPN and PNP libraries from @Bordodynov so you can adapt things to your needs. I make no representation for the efficacy of these models.

Thanks for the info Papabravo, I appreciate it. I am still getting a "missing nodes" message. I think that I followed the
LTSpice instructions correctly. I am at a loss.

 

A simple way is just to import the models info into the standard.bjt model subfolder in the CMP folder.
The main disadvantage of this is that it will just use the standard NPN or PNP transistor symbol, which doesn't indicate that it's a Darlington.

 

Thanks for the info Papabravo, I appreciate it. I am still getting a "missing nodes" message. I think that I followed the
LTSpice instructions correctly. I am at a loss.

Did you run any of the examples I provided to you?

Additionally, I'm sorry you were unable to make use of the files I provided. If you are not comfortable with manipulating files in LTspice, knowing what to do can be problematic. Give me some hint about what you are trying to do and I'll see if I can put together something easier for you to use.

You could also .zip up you directory and attach it to a message. I might be able to diagnose your problem

 

Did you run any of the examples I provided to you?

Additionally, I'm sorry you were unable to make use of the files I provided. If you are not comfortable with manipulating files in LTspice, knowing what to do can be problematic. Give me some hint about what you are trying to do and I'll see if I can put together something easier for you to use.

You could also .zip up you directory and attach it to a message. I might be able to diagnose your problem

I want to study a simple class AB amplifier circuit using darlington power transistors. I thought that
perhaps the TIP110 / TIP115 or the TIP120 / TIP125 might be suitable. The reason that I want to use
darlingtons is because of the high input impedance that can be achieved thereby preventing
a previous voltage amplifier from being loaded down. I haven't done any more than think
about it and try to get spice models. I like to run a spice sim before I breadboard a circuit just to
see what I can expect in the real world.

Thanks,

RS

 

I want to study a simple class AB amplifier circuit using darlington power transistors. I thought that
perhaps the TIP110 / TIP115 or the TIP120 / TIP125 might be suitable. The reason that I want to use
darlingtons is because of the high input impedance that can be achieved thereby preventing
a previous voltage amplifier from being loaded down. I haven't done any more than think
about it and try to get spice models. I like to run a spice sim before I breadboard a circuit just to
see what I can expect in the real world.

Thanks,

RS

You said that you are getting errors, and I asked you if you ran any of the examples that I included in the .zip file. You did not answer that question and you did not send me your example that produces the errors. Can you please do one or the other, preferably both? If I had an example of a class AB amplifier, implemented with Darlingtons, it would help me to help you.