Sziklai pair?

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Why don't them make them in a single package like Darlingtons?

While on the subject of "why don't they make 'em", why don't they make a CMOS pair in a package? It would have 4 pins but would eliminate the need for a drain (or collector) resistor.

I'm not an E.E., just an ignorant programmer. But you probably knew that already.

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Probably because there is no demand for them.

Leon

Leon Heller G1HSM

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But Sziklais are better than darlingtons. I know that because I read about them on wikipedia. :) Lower turnon voltage, you know.

They are harder to spell. I suppose that's a marketing man's nightmare. :)

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They would cost a lot more to make (PNP and NPN) and the turn-on voltage is irrelevant in most applications. They are often used when made with discrete devices, of course.

Leon

Leon Heller G1HSM

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But it may be relevant in my application. One more sign they're out to get me. :)

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They sell CMOS pairs in 16 pin and 14 pin DIP packages. I suppose they make them in SMD packages also. They call them hex buffers, with or without Schmidt triggers.

Why is it that everyone else wants six, but I only want 1?

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I think that transistor arrays with both NPN and PNP transistors are available. You could use one of those.

Leon

Leon Heller G1HSM

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Why does everyone insist on asking obscure questions without mentioning their application? Often times, when you can't find the part you are looking for, it's because of a misapplication.

They do make buffers and schmitt triggers in single device packages, check at Digikey.

I like cats, too. Let's exchange recipes.

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I thought I was the only one who asked obscure questions, but if everyone does it, I don't feel so bad. :)

I'm just hacking around here, trying to figure out the easiest way to cobble together a circuit. I didn't find anything available in through hole except 14 pin or more. The smallest package I found for SMD is 5 pin. I'll keep that in mind, in case I make a PC board.

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I have some long to explain old theories (conspiracy ones? ;)) about why Sziklai's are not so common as simple darlington, but the most promising is that a common place where one expects to find them is at audio power stages, where there is a big difference between the 'first stage' and the 'second stage' in power and current sizes.

That makes usually more attractive to use a discrete smaller 'first stage' with better gain and performance than if they are used in a whole (power - TO3) package.

But anyway, given the existence of MOSFET and IGBT's that are easier to operate and have 'beefer capabilities', why one needs power BJT's anymore?

Well, that leads me to question the still common use of thermoionic valves, but this is another flame war.

Guillem.
"Common sense is the least common of the senses" Anonymous.

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I would say more of a steam war... ;)

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Well, I have used that circuit a number of times without ever calling it "Sziklais". Probably as early as 1965.

Several references refer to its use as an output stage. In that context, you really do NOT want single package devices just because of power dissipation. For lower power applications, there are so many options that I don't see that it matters whether you use "Sziklais" or not. So, if you integrate it, what difference does it make what is inside?

As for the "Sziklai pair", until the last few years, it was really difficult to put an NPN and a PNP on the same die. If you CAN'T put it on the same die, there is no economic benefit.

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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Quote:

Well, I have used that circuit a number of times without ever calling it "Sziklais". Probably as early as 1965.

Scofflaw. Hijacker. Intellectual-property pirate. And since before it became fashionable.
Quote:

# U.S. Patent 2,762,870 Push-pull complementary type transistor amplifier. G.C.Sziklai, September 11, 1956
# U.S. Patent 2,791,644 Push-pull amplifier with complementary type transistors. G.C.Sziklai, May 7, 1957

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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I agree to all of the above. We were never challenged and never knew of the existence of the patents. Now, I do, but they have probably expired.

With respect to the "pair" if the initial discussion, I believe that this configuration is more prone to problems with collector-base leakage. Ancient transistors had more leakage but it still is not zero and still depends on temperature. Using as a switch should avoid this. However, as a switch, I don't think that the turn-on and turn-off will be symmetrical. in a few cases, that is good, but mostly not. It is also a problem with Darlington unless a shunt resistor is added between the base and emitter of the second transistor.

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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Quote:

I agree to all of the above. We were never challenged and never knew of the existence of the patents. Now, I do, but they have probably expired.

LOL--and so has the statute of limitations? ;)

I hadn't heard of "sziklai" before and the patents popped up in my Google search. Maybe in the Wikipedia article? [and I posted the excerpt without attribution, so I am now in the same boat as you are]

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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I remember reading about sziklai configuration in the Art of Electronics. Never heard it since, but I do have heard of complementary darlington since.

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Just caught a new product announcement for Linear Tech LT3092 Current Source IC, Wow, it has one of these things in it, plus an op-amp as part of the constant current control loop. Takes two external resistors. Very clever.

The interview about the device never mentions "Sziklai"!

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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It's a slightly different arrangement (actually it's just upside down), but the UDN2595 had eight of them. The Allegro part is discontinued but there were multiple sources. This didn't have a voltage threshold, any input current to ground would turn it on - kind of like a non-inverting muscle for logic outputs. One drawback is it was extremely slow, typically 10-15us turn off delay. That didn't matter if you were driving relays.

Attachment(s): 

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ka7ehk wrote:
Just caught a new product announcement for Linear Tech. , it has one of these things in it,

The interview about the device never mentions "Sziklai"!

Jim

A name nobody this side of Hungary can pronounce or spell. Gee, I wonder why it wasn't mentioned. :)

I have to chuckle over his name. George Clifford Sziklai. Could it be that he changed his first and middle names when he came to America, and left his last name alone?

Or is every third person in Budapest named George Clifford something? :)

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CD4007

Dual Complementary Pair Plus Inverter

 

Voila, Back from the 80-ies. (70-ties?, older?)

Doing magic with a USD 7 Logic Analyser: https://www.avrfreaks.net/comment/2421756#comment-2421756

Bunch of old projects with AVR's: http://www.hoevendesign.com

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steve17 wrote:
... but I only want 1?

 

 

Last Edited: Fri. Oct 14, 2016 - 01:43 AM
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Seven (7) years later...

 

Ross McKenzie ValuSoft Melbourne Australia

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A name nobody this side of Hungary can pronounce or spell. Gee, I wonder why it wasn't mentioned. :)

 

I have to chuckle over his name. George Clifford Sziklai. Could it be that he changed his first and middle names when he came to America, and left his last name alone?

Or is every third person in Budapest named George Clifford something? :)

 

Now that's quite absurd. I can assure you that is absolutely not true.

Best regards,

George C. Menahem

 

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LOL!

That's classic!

David

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I had to read it twice, and now I'm still laughing!

 

JC

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steve17 wrote:
But Sziklais are better than darlingtons. I know that because I read about them on wikipedia. :) Lower turnon voltage, you know. They are harder to spell. I suppose that's a marketing man's nightmare. :)

 

Not long ago, I read the same wikipedia article and thought the same. But I also thought "surely there is a very good reason...", so I built a Sziklai pair with a 2N3904 and a 2N3906. I quickly discovered the problem: You can't turn off a Sziklai pair, it's not a good switch.

 

See this diagram:

Sziklai pair

 

Even if VIN goes to the positive rail, VOUT cannot go to the rail, it maxes out at rail-VBE (~4,3V in this case) because of the NPN stage VBE drop. A transistor that cannot be fully turned off is not very good.

 

Edit: Oh, this was resurrected, didn't even notice. Anyway, this is my take on why Sziklai pairs aren't as popular as Darlingtons.

Last Edited: Fri. Oct 14, 2016 - 09:24 PM
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valusoft wrote:
Seven (7) years later...
Oops, blame it on me.

Thread seems to be chugging along happily now though :)

Doing magic with a USD 7 Logic Analyser: https://www.avrfreaks.net/comment/2421756#comment-2421756

Bunch of old projects with AVR's: http://www.hoevendesign.com

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My threads never die.  They just get better with age.  wink

 

This thread is so old I've forgotten all about a Sziklai pair, and why I wanted it.

Last Edited: Mon. Oct 17, 2016 - 01:46 AM
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You can't turn off a Sziklai pair,

As with a Darlington pair, a resistor (e.g., 100Ω–1kΩ) is usually connected between Q2's emitter and base to improve its turn-off time (i.e., its performance for high frequency signals).[1]

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