beast. 50 cents.

I think the upper output pair needs to be an ordinary Darlington for it to work right, or the Sziklai pair needs to have its polarities swapped.

If it's designed to operate Class B, then I think the upper pair should be an ordinary Darlington.

Yes. The three diode bias string suggests an upper darlington. But the swing spec is symmetric. Interesting.

Anyhow, I'm probably going to put a dozen of these on a board, driving

24 transformers, a multi-channel LVDT/synchro simulator.

John

Hmm. It says on the first page that it has no crossover distortion, so that makes me think it must be class AB, so it must be a Sziklai pair in the upper position, like this:

Sziklai pairs supposedly have inherently lower distortion than the ordinary Darlington.

Two emitter drops, but three diodes I would think implies class AB, since on an IC they can manage all the diode/transistor parameters and set the idle current exactly in a way you couldn't using discrete components.

Does the IC have current limiting? It doesn't have any info about safe operating area or anything. Will it do 1 amp peak at max output voltage into any big old inductor one would hang off the output without destroying the output transistors?

That's because it isn't, the pull-up pair should have the PNP-NPN exchanged, NPN: base at top of diode string, NPN collector to PNP base, NPN emitter to OUT, PNP emitter to V+ and PNP collector to OUT.

Ain't no such thing as a monolithic high current PNP, so your guess as an ordinary Darlington would be right. ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

But then it would only need two diodes in the bias string.

John

So how do they achieve "No deadband crossover distortion"? I would think that implies they're not running it straight Class B, but if there's a Darlington and a Sziklai that's 3 Vbes, and if the diode drops are comparable that means it's running class B. Do they jigger with the diode/transistor emitter area in the bias string relative to the Vbe drops of the output transistors to get extra bias voltage?

looks a lot like a LM386. What would you use it for?

40V is nice 1A is nice But the package dissipation can't support anything I can imagine.

Thats to prevent the Chinese from copying it.

I've used this device a couple of times for communication plus power feeding over long lines. The high voltage, high current capability and the thermal protection make it an ideal device for such applications.

AFAIK there is no replacement with the same value for money.

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Failure does not prove something is impossible, failure simply
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nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------

There's no telling with that thermal protection bias control scheme. I thought the industry overcame the problem of low beta on the high current monolithic PNPs. It probably is just a Darlington.

Ve have our vays ;-)

I have a true class-AB, but no one will pay for it... so I only implement it in my own personal stereo. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

The 386 isn't a real opamp, like the TCA is.

I'm designing an LVDT/synchro simulator. It will have 24 channels, each a DAC, a power amp, an SSR, a transformer, and an ADC.

ftp://jjlarkin.lmi.net/V545%20Ct%20DiagT.gif

The idea is that any channel can accept a sinewave input, or make a sinewave output. All the FPGA has to do is connect different channels properly to simulate various inductive sensors, and provide a few DDS sine synthesizers for utility. Later on, with a lot more work, we could make it digitize LVDTs and synchros and resolvers. Hmmm, I suppose we could train it to do AC voltage and power measurements, too.

The TCA will be the power amp that drives the transformer. It is overkill, but there aren't many opamps between wimpy ones and this beast. I like that it swings close to the rails. Cheap, too.

The SO16 package has four pins in the middle that are apparently the lead frame, so it can be heat sunk. Somewhat.

John

I recall the LH0063 "Damn Fast Buffer Amp" with 6000V/us slew rate. I wonder if it was really a POS in every other way.

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If you call 3V close to the rails :-)

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------

It swings +-14.2 typ from 15 volt rails at 100 mA loads. Does anything else do that?

John

The LH0063 was a hybrid circuit... a main IC chip plus discrete PNP & NPN chips.

Similar in construction to the Motorola MC1524 1W audio power amplifier of the 1960'2, of which I was a designer (and had forgotten until Tom's post)... except it had _4_ discrete chips, 2xNPN and 2xPNP arranged in "Sziklai pairs"... makes me wonder if it shouldn't be called a Solomon-Thompson pair. When did Sziklai claim the configuration? ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

No, it's a beautiful device. I have about a dozen left, and about 20 of its little brother in the weird package, the LH0033, as well as probably

30 of its short-lived descendant, the LH4009. (For some weird reason National came out with a whole bunch of hybrid amplifiers in the 1989 databook that were gone from the 1990 databook. Some of them were very good, but they didn't catch on.)

Cheers

Phil Hobbs

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Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
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845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

That is typical. IIRC when powered from single 24V it can swing to max. 21V guaranteed.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------