Philips UCD application note

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>120dB SNR?? ... and with this single ended version? hmmmmmm.

It's an OK read, but you'll learn more from going to the hypex website and reading an actual paper written on it by the guy who actually knows something of it, and much more yet from the posts on this forum if you go back far enough.

Did they give the "most important" information or the most basic? According to Bruno's comment the last time this was brought up.... this is all they've got to give on it. Funny. I guess that explains them having "serious problems implementing it" (so a little bird told me)... guess they should have stayed on his good side?

Funniest part:

"Again, any changes are left the responsibility of the experimenter, but assistance from
Philips will be available through the local sales representatives."

What part of that do you think gets removed upon the next revision of the datasheet.

Ivan, about the pic.. it's your typical microfilm quality, they must have stolen it when he had his back turned :D
 
Well, there's alot of reading you can do in the areas I mentioned, but if you really want to get your feet wet and jump in head first, just build this sucker and use as advised. I wouldnt' expect that performance from it though.

This cheapness is likely to be the reason why Philips can't make use of it! So if you want better... you're going to have to dig up a little more on it, but it's all out there.

EDit: You're not going to want to judge a Hypex version based on this sucker though!
 
well, I'm not really looking for the "best class D that money could buy" thing but something quick and dirty to drive a pair of subs. probably build this first as is and work up to a higher power version when I get a feel of things.

edit also:if you got a link for a schematic with more power and better performance as is then I'm all ears (or eyes.:D )
 
that's an interesting link. appreciate it.

i am still struggling with mine - which more and more looks like a mosfet driver issue but I will report back when I get it fixed.

classd4sure, what is the "most important" information? I think a good circuit is one that is first of all robust. If something is that quirky, there usually is something foundamentally wrong with the circuit.
 
fokker said:
that's an interesting link. appreciate it.

i am still struggling with mine - which more and more looks like a mosfet driver issue but I will report back when I get it fixed.

classd4sure, what is the "most important" information? I think a good circuit is one that is first of all robust. If something is that quirky, there usually is something foundamentally wrong with the circuit.


I don't know I tend to think alot is equally important oppositly than they've pointed out. You don't have to worry about it though, because all that stuff doesn't appear in their version of it :)

You're using a driver IC right? Maybe post some experiences/schematics to your thread and we can help you out with whatever issues?

Cheers,
Chris
 
janneman said:



Yes, that's logical. It is more complex therefore it must work better. Maybe I can add anothe 10 components to make it more complicated so it even works more better.

Jan Didden


Guess I should not have deleted my prior post.

Here it roughly is again.

Bruno's designs are probably the most elegant I've ever seen. As I'm sure you know patents rarely include "everything" towards a preferred implementation. This is such a case.

If you just go to the Hypex website and read their AES paper on UcD you'll instantly spot one obvious difference... differential feedback. There's yet another improvement which just makes it a more robust circuit, and is needed at higher power, that often appears on this forum. There's a few more things that set it apart from this version as well that we don't necessarily know about. Philips doesn't have any of this, and I guess they'd rather push the digital envelope with far more complex circuits than put the little bit of effort required into fixing this one up a little.

I got word from someone that Philips basically gave up on this version of UcD because they had alot of problems in implementing it. Why is that when Hypex has no such issues, and neither does the vast majority of their customers... why only Philips .... who own the patent? Because, all they have on it is the "as seen on patent" version. Several have managed to build diy versions based on designs floating around here, that are better then what you see in this datasheet by philips in some ways. They did it without even the use of a scope, which is absurd. I'm one of the first to have done so too. Ivan was also one of the first to be playing around with his own discrete versions of it if I'm not mistaken.

It's not a question of complexity being better. They didn't share this because it's their best amp going, they shared it because they gave up on it, so why not use it to push their transistors instead..
 
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I know the guy at Philips who built this and I've seen the amp (they made about 30 PCB's). I never heard it but another guy at Philips (an applications engineer) compared it to his Arcam Alpha (DIVa85 I believe). He told me it was pretty impressive - good sound.

Layout absolutely critical especially around Mosfets (circuit is optimised for the mosfets shown, so do not change them unless you are in a postion to do some tweaking) and output inductor. All traces short as possible. In fact, trhe mosfets on the board are back to back with the hesatsink in between them in ordeer to get the traces as short as possbile.

I guess this circuit is not as easy to implement as an IC based design, but if you are a manufacturer looking for a high powered design, this makes a lot of sense because you can get the repeatability from board to board. Nevertheless, its still a fun circuit I imagine to play with.

for me personally, I stick to standard linear designs!

bonsai
 
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