Howdy all,
I've made a few little LM380 headphone amplifiers off some internet schematics, and they've been great fun. Now I'm wanting to take things another step.
I'd love some resource material on the hows and whys of the various supporting passives around the chip, i.e. why is there a cap here or there and why is it the value it is etc.
Would love to gain a deeper understanding of these circuits and design some of my own, so this seems the logical place to begin
Thanks!
Karl.
I've made a few little LM380 headphone amplifiers off some internet schematics, and they've been great fun. Now I'm wanting to take things another step.
I'd love some resource material on the hows and whys of the various supporting passives around the chip, i.e. why is there a cap here or there and why is it the value it is etc.
Would love to gain a deeper understanding of these circuits and design some of my own, so this seems the logical place to begin
Thanks!
Karl.
Just had a look at a .pdf of it. That should keep me busy until the end of time haha.
I can see why its a yardstick. Cant wait to sink some time into it.
You may want to look at an application note from the chip mfr. These can be fairly helpful.
http://www.ti.com/lit/ds/symlink/lm380.pdf
http://www.ti.com/lit/an/snaa086/snaa086.pdf
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In addition to the book Mooly recommended, there are excellent texts from Bob Cordell and Doug Self on exactly that subject. If you want a course in a book, those two are the closest you will get.
Each book treats the subject a little differently, but completely. These two authors don't agree on everything, so you will end up with two viewpoints. All three texts belong on your bookshelf. I think every member serious about audio electronics has these three books, plus others on their bookshelf. I do.
You're beginning on a wonderful journey!
-Chris
Each book treats the subject a little differently, but completely. These two authors don't agree on everything, so you will end up with two viewpoints. All three texts belong on your bookshelf. I think every member serious about audio electronics has these three books, plus others on their bookshelf. I do.
You're beginning on a wonderful journey!
-Chris
While not the depth of the books already mentioned, take a look at the articles/projects at passdiy.com and firstwatt.com. You'll get a third design philosophy in a fun to read style. I really enjoyed the Zen amp series as Nelson "Papa" Pass walked through the design from as simple as can be with good performance through several iterations and side trips that improved various aspects. Not as number heavy as the books, but an easier place for me to start.
You're embarking on a journey that will be a lot of fun. Letting the magic smoke out once in a while means you're learning.
You're embarking on a journey that will be a lot of fun. Letting the magic smoke out once in a while means you're learning.
Chips or opamps specifically, are a mainstream electronics topic usually covered in standard, engineering-oriented texts. This can be really dry reading unless that's your field of endeavour.
Self also wrote this interesting work which covers a lot of ground and personal experience in pro, line-level audio. It has more content in line with opamp audio designs which may be what you are looking for: https://www.amazon.com/Small-Signal-Audio-Design-Douglas/dp/0415709733
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> supporting passives around the chip
That's a very narrow question. Much less than Self Cordell Pass et al are answering.
Basically-- if they could have put those parts in-chip, they would have. Less money on externals is more loot for the chip-maker. So the reasons they are external are rather specialized.
Which means, as said, the specific chip app-notes are your best stepping-stones. These "obsolete" chips fade, and their datasheets faded faster (my '380 app-note is on crumbling brown paper). Thank Rayma for the links which can be hard to find now.
Note/know that LM386 and LM389 are the basic '380 design, smaller/cheaper, and had their own app-notes not entirely copies of the '380 sheets.
Power Integrated Circuits: Physics, Design, and Applications, Paolo Antongnetti, has a few pages on audio power chips and "minimum external parts". The little bits of audio-amp information are in a sea of semiconductor fabrication data which was very useful if you were working for a chip maker in the 1980s, less essential today.
www.abebooks.com/book-search/isbn/0070021295/
https://www.amazon.com/Power-Integrated-Circuits-Physics-Applications/dp/0070021295
That's a very narrow question. Much less than Self Cordell Pass et al are answering.
Basically-- if they could have put those parts in-chip, they would have. Less money on externals is more loot for the chip-maker. So the reasons they are external are rather specialized.
Which means, as said, the specific chip app-notes are your best stepping-stones. These "obsolete" chips fade, and their datasheets faded faster (my '380 app-note is on crumbling brown paper). Thank Rayma for the links which can be hard to find now.
Note/know that LM386 and LM389 are the basic '380 design, smaller/cheaper, and had their own app-notes not entirely copies of the '380 sheets.
Power Integrated Circuits: Physics, Design, and Applications, Paolo Antongnetti, has a few pages on audio power chips and "minimum external parts". The little bits of audio-amp information are in a sea of semiconductor fabrication data which was very useful if you were working for a chip maker in the 1980s, less essential today.
www.abebooks.com/book-search/isbn/0070021295/
https://www.amazon.com/Power-Integrated-Circuits-Physics-Applications/dp/0070021295
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One place to start would be the application section of the LM3886 data sheet. You can also find some info on my website, specifically the Taming the LM3886 pages. In the resources section of my website, I also list a bunch of references that are good to flip through. If you are just starting out, The Art of Electronics may be the better starting point, though. A new edition was released last year I think.
Tom
Tom
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