TIP162 (Darlington NPN) Substitute?

[TimLaw]

Hi everyone,

My dad loves his car and since he's retired he can spend a lot more time with it than when he was working. I saw this Velleman K2543 kit which is a electronic ignition amplifier, similar to the ignition boxes you see in high performance muscle cars.

I don't have too much faith in the junk Velleman bundles in their kits, and I'm less comfortable with them running the ignition system on a car...so I'm going to etch the PCB myself and source the components myself also.

There's one problem. I was able to find every component except for a Darlignton transistor called the TIP162, which was originally manufactured in the 70s by Bourns. They are no longer made, and any replica you buy of it is from either NTE or some no-name brand. I'm not comfortable with using those either. (I can't imagine Velleman is packaging a genuine Bourns chip either.)

So, my question is: Can I choose a different Darlington NPN transistor with specifications exceeding those of the TIP162 and drop it in?

I found this ST Darlington that has Max operating specs that are much better than the TIP162: https://www.mouser.com/ProductDetai...=sGAEpiMZZMupZfs/wBb3DGpkiAxa96AGlAaesqTuzAc=

Can I simply use this one instead? I don't know how Darlingtons work, so I'd be curious if I could just use that BU941 from Mouser. Is it possible?

Thanks.

 

[crutschow]

A quick comparison of the main parameters from the data sheets would indicate that the BU941 does have higher ratings and you can use it in place of the TIP162.

A Darlington is just a transistor configuration of two transistors in one, where the first transistor's emitter is connected to the second transistor's base. Its purpose to to give a much higher gain (beta) than a single transistor, so it requires much less base current to turn on for a given collector current. It's disadvantage is that it has a higher collector-emitter saturation voltage (voltage when switched on) then a single transistor.

 

[TimLaw]

Thanks for the quick reply!

I think there might be some inductance issues if I try running wires to the TO-3 package, so there is also this big TO-220-type package that ST offers with zener protection already built in, and with an insulated tab. Granted, it might actually have specs that are very close to the TIP162. Some are a bit below and others are a bit above the TIP162. But with sufficient cooling, I think it would also be fine. This is the one I am talking about: BU941ZPFI STMicroelectronics Darlington Transistors

This packages isn't quite as good as the TO-3 package I linked. Do you think I'd run into problems using the TO-3 package and then running maybe 1inch wires off of the legs/case to the PCB?

Yeah I didn't know if it was more than just a transistor. Thanks.

 

[crutschow]

The package type determines the maximum power dissipation (with a heat sink) so if that's sufficient for your application you're ok.

The inductance of a few inches of wire is negligible for your application.