# Talk:Darlington transistor

WikiProject Electronics (Rated Start-class, Mid-importance)
This article is part of WikiProject Electronics, an attempt to provide a standard approach to writing articles about electronics on Wikipedia. If you would like to participate, you can choose to edit the article attached to this page, or visit the project page, where you can join the project and see a list of open tasks. Leave messages at the project talk page
Start  This article has been rated as Start-Class on the project's quality scale.
Mid  This article has been rated as Mid-importance on the project's importance scale.

Where does the name "Darlington" come from..?

Google search for "darlington transistor name" came up with this: [1] - the answer is Bell Labs researcher Sidney Darlington (1906-1997). I'll put a note on the subject page. -- Tim Starling 22:21 Oct 29, 2002 (UTC)

## Spam??

There is something wrong with this article, I've tried to revert he spam, but I still see the spammed version. And it's definitely not in my cache. :-\ —This unsigned comment was added by Pieffe (talkcontribs) .

Seems OK now, last revision I see is 12:10, 16 March 2006 Ugur Basak m (Reverted edits by 80.249.52.136 to last version by Ugur Basak). Femto 13:01, 22 March 2006 (UTC)

Putting a darlington pair together has a 1.2v voltage drop. I tried giving a common base and collectors in my pair so is that sill a darlington or paralelle transistor as the darlington circuit was still intact but bases were connect to each other and the collector to collectors were connected but the emitter of the first one still fed into the base of the second transistor? It seems to work like paralelle but it also has some darlington aspect? So if it is something new then I will call it a Kappatron. Travbm 5-19-2016 — Preceding unsigned comment added by Travbm (talkcontribs) 14:23, 19 May 2016 (UTC)

## Input and Output Impedances?

"Electronics Principles and Applications", 3rd edition by Schuler states that the darlington transistor has a high input impedance but does not say much else. Any more exact information in the input and output impedances. Any examples of the Darlington Emitter Follower? That would be helpful.

## References.

I think a good part of this article is taken from The art of electronics, Horrowiz Hill, 2.16 pag 95. Shall we cite it? Is not verbatim, but is definitely from there. --Pieffe 18:13, 1 April 2006 (UTC)

I didn't write the article, but I did add some information to it using AofE as a reference. However, it was not lifted verbatim, just used as you would use any reference work in an assignment, etc.. So, feel free to add a citation. Graham 08:36, 2 April 2006 (UTC)

## wrong

The current gain should be b1*b2 + b1 + b2 I think.

That can't be right since the current gain should be zero if either b0 or b1 were zero. Roger 19:53, 22 May 2007 (UTC)
Actually, if you do the math and solve for the compound transistor's Ic and Ib you'll get Ic = (b0 + b1*(b0+1))*Ib which means b = b0*b1 + b0 + b1.
Now looking at the pair and assuming that all the junctions are good, assuming that b1 (the output transistor) is 0, the overall current gain is b0. This is because the first tranistor's emitter current will flow through the BE junction of the second transistor to the compound transistor's emitter. In this situation, the collector and emitter currents of the darlington pair are given by the collector and emitter currents of the first transistor.
If the first transistor has a current gain b0 = 1 but still, its junctions are intact, the overall current gain will be b1 because the base current for the second transistor will flow through the (intact) BE junction of the first transistor.
The relation for the current gain b = b0 * b1 is only an approximation and valid only if both b0 and b1 are high enough. But in the case of a power tranistor, b1 is usually quite smaller than b0 so you might get some error if you use the simple relation (i.e. b0 = b1 = 250 you'll have true b = 63k over b = 62.5k, that is 0.8% error, but if you have b0 = 80 and b1 = 20, true b = 1700 over b = 1600, that is 5.9% error)89.136.39.53 (talk) 09:11, 7 March 2009 (UTC)Apass

## bandwidth of darlington amplifier

HOW TO DESIGN A DARLINGTON AMPLIFIER OF A GIVEN BANDWIDTH?

IS THERE ANY DESIGN FORMULA? —The preceding unsigned comment was added by 61.2.226.29 (talk) 18:32, 10 February 2007 (UTC).

I don't know where this fits. But has anyone tried putting a tunable LC circuit between the emitter of transistor one and the base of transistor two for adjusting frequency with capacitance adjusting frequency and current to the base of T2? — Preceding unsigned comment added by Travbm (talkcontribs) 20:49, 20 May 2016 (UTC)

## What exactly is a "Darlington" ??

The article seems indecisive throughout as to the essential nature of a Darlington arrangement. It begins by describing the Darlington as a single device but goes on to suggest that an equivalent configuration of discrete devices can still be a "Darlington".

I'd always understood "Darlington pair" to refer to the circuit arrangement (not to the physical construction), but Darlington's early involvement with integrated packages makes me wonder if he (at least) considered his essential contribution to be the integration. Unfortunately, it seems that he died almost ten years ago, so the obvious source of an authoritative definition is gone. Is there a comparable authority? Mike Shepherd 14:42, 22 May 2007 (UTC)

## Unclear content

The articles states that "many common transistors with high gains have a low current threshold". Can anyone say what this means? I think maybe the intention was to say "low current rating" (no threshold involved). If so, the word "threshold" should go. Mike Shepherd 14:42, 22 May 2007 (UTC)

Since there has been no reply to this in over nine weeks, I have removed the corresponding text. Mike Shepherd 22:41, 27 July 2007 (UTC)

## Darlington transistor vs Darlington pair

I think "Darlington pair" is the more common name for this arrangement and more accurate since it's really two transistors. Any objections to me moving the page? Roger 18:21, 22 May 2007 (UTC)

I support that. Although we may say "Darlington transistor" in casual conversation, the article would be better by avoiding that term. Mike Shepherd 08:14, 24 May 2007 (UTC)

## Gain split in integrated Darlington transistors

Integrated Darlington power transistors are generally made as low-current/high-gain then high-current/low-gain 'pairs' on same die, but do non-'Power' Darlington or 'super-beta' devices have an even gain split ? I'm trying to resolve possible ~45 /~100 split in 6n139 split-Darlington opto-coupler as valid or error. Nik 2213 (talk) 15:06, 30 August 2010 (UTC)

## hFE vs. hfe

It's my understanding that hfe refers to small signal variations in beta, while hFE refers to the overall gain where IE = IB * hFE and ΔIE = ΔIB * hfe, where IE is the emitter current, IB is the base current, ΔIE is the change in IE, and ΔIB is the change in IB. In this article, the two terms are equated. I know that it's not uncommon for the two terms to be used interchangeably, but it seems like it would be a good idea to explain how they should be used instead of potentially adding to confusion for beginners like myself. This is all based upon my reading of Horowitz & Hill Art of Electronics, 2nd Edition, 1989.Rben13 (talk) 12:45, 11 July 2011 (UTC)

There is no need to even discuss this in this article. Removed all three symbols. As you'll find in TAoE, hfe and hFE are distinct, but for BJT's it is often more important that they are both relatively large. So it's common to see ${\displaystyle \beta }$ instead, but even that gain is rarely used in biasing calculations for BJT's. Regardless, the Darlington's cascading effect applies to each gain, and so there's no reason to point one out. There's certainly no reason to point them all out with the fear that it will equate them in the reader's mind. —TedPavlic (talk/contrib/@) 17:48, 11 July 2011 (UTC)

## Darlington is not super-beta

Currently it is stated that darlington pairs are also called "super-beta" transistors. This is incorrect. A super-beta transistor is a single BJT made with a very narrow base region. See e.g. this note from Analog Devices. Removing the paragraph. — Preceding unsigned comment added by Mpa (talkcontribs) 17:29, 14 February 2013 (UTC)

## Can someone simplify the: increased "saturation" voltage and doubling of voltage info

The drawbacks section is a bit too technical for general use. I have modest electronics knowledge but not following the two drawbacks mentioned. It is also worth noting the original section explaining how the pair works is great and a lot more accessible to understanding.

I think this is valuable point since ULN2003 chip driving stepper motors is common with microcontroller enthusiasts these days and understanding Darlington IC chips would be useful to many beginners. — Preceding unsigned comment added by DiscoverYellow (talkcontribs) 14:33, 21 April 2014 (UTC)