You right. This kind of design is a compromise to make it more accessible by replacing a standard 3 pins regulator. The chip it perform better when is used just close the the target circuit, with GND plane around traces, and so on. But then it will be accessible only to those who will use the whole assembly. Definitely not so popular...
In my case, I`m using it mainly in my new designed DAC system...
But the real destroying of the chip parameters is using it (nonsense) to regulate a SMPS output...
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Anyway, it looks much better when is to regulate a serial PSU output...
You can see more here: http://www.diyaudio.com/forums/power-supplies/254098-king-regulators-adm-7151-a.html#post3879757
Coris, the module for which I started the thread is ONLY a regulator board. Nothing else. It doesn't matter what one might use before or after it.
It is my PERSONAL choice to use it with an smps.
Would you please stop dissing my efforts? After all I live in a free country where I can do whatever I want. You posted in the first page also another post trying to lessen my effort and trying to advertise yours. Ok we get it. You are the guru and you do it best. Is that enough now? Can we go back to more constructive comments?
Thank you.
It is my PERSONAL choice to use it with an smps.
Would you please stop dissing my efforts? After all I live in a free country where I can do whatever I want. You posted in the first page also another post trying to lessen my effort and trying to advertise yours. Ok we get it. You are the guru and you do it best. Is that enough now? Can we go back to more constructive comments?
Thank you.
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The comments can be for or against something... This forum does not belong to a specific country (more or less free) and is open to all kind of comments (into the rules limits).
At least I sustained my comments with some proves... and you are of course free to do what/how you want, accordingly to your personal choices. Good luck!
P.S. One should at least tolerate some criticism...
At least I sustained my comments with some proves... and you are of course free to do what/how you want, accordingly to your personal choices. Good luck!
P.S. One should at least tolerate some criticism...
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Lets keep this friendly and on topic folks.
Coris, constructive criticism is fine if its a valid point you have to make but please don't use this thread as a sounding board for your own currently running thread.
I for one am going to keep an eye on this IC.
It is not often I see low noise addressed in a data sheet and Coris has shown the really low noise it can provide even using a three terminal board fed with a SMPS.
Thank you Coris for bringing this IC to our attention and Nikitas for posting some data and sparking additional interest.
I think it is great.
I wonder if there is a negative regulator with similar characteristics available.
🙂
It is not often I see low noise addressed in a data sheet and Coris has shown the really low noise it can provide even using a three terminal board fed with a SMPS.
Thank you Coris for bringing this IC to our attention and Nikitas for posting some data and sparking additional interest.
I think it is great.
I wonder if there is a negative regulator with similar characteristics available.
🙂
OK, makes sense.
What I'd be worried about here is that :
- The switching PSU generates, say 50 mV ripple @ 30 kHz
- The capacitor on the reg board... say 100µF... has an impedance of 60 mOhm at this freq, let's add the impedance of wires, round it up to 0.1 ohm.
- Therefore, with 50mV ripple, a ripple current of 0.5 amps will go through the capacitor... and through the GND pin of the regulator
- With, say, 10 mOhm contact resistance (if you use a socket) or even 1 mOhm (soldered) a voltage much larger than the regulator noise will be added to its ground reference, and thus to its output voltage
Therefore the main problem with the 3-pin format is not the regulator ground current (which is very low) but the capacitors. This makes the regulator PSRR irrelevant. So the input caps should be on the main board.
3 pin format only works if the GND pin carries no current ! This means the IN and OUT current are the same. No capacitors allowed.
The same could be said for the output caps,if the load draws a variable current...
If the output caps are on the reg module, then they can't be on the main board, which is a problem. So IMO it is better to leave the caps on the main board.
You can add a little PI filter to your SMPS, cap, ferrite bead, cap. Murata gives all the spice models for their ferrites on their simsurfing website.
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peufeu
Or you could place a series inductor on the input line to isolate the SMPS noise.
Or put a common mode inductor on both the + and - supply to the regulator board.
Or you could place a series inductor on the input line to isolate the SMPS noise.
Or put a common mode inductor on both the + and - supply to the regulator board.
There are not filtering caps on the regulator board (at least in my design). But the caps recommended by the producer for decoupling the in/out of the chip, as the caps necessary to the chip to function.
When a such 3 pins module is to be used, the rest of the filtering/decoupling caps still be in place as designed on original device...
Just throwing out some ideas for those that want them.
Or have some extra parts they want to use.
I do agree that sometimes complicated designs get...complicated.
🙂
Ok so one solution is transformer+rectification+filter+regulation
The other is smps+regulation.
The first costs more and occupies much more space.
The smps can be a wall adapter. What is so complicated about that?
I don't have the boards at hand yet. I will have them so though and I have a couple of ideas to try. Please be patient.
The other is smps+regulation.
The first costs more and occupies much more space.
The smps can be a wall adapter. What is so complicated about that?
I don't have the boards at hand yet. I will have them so though and I have a couple of ideas to try. Please be patient.
Used in JG buffer
How about something like this built into the reg board (might be too large?) or as a separate board to attach close to the smps and feed the reg board from this?
http://www.diyaudio.com/forums/digi...jg-buffer-boards-betatest-17.html#post3636317
How about something like this built into the reg board (might be too large?) or as a separate board to attach close to the smps and feed the reg board from this?
http://www.diyaudio.com/forums/digi...jg-buffer-boards-betatest-17.html#post3636317
What do you mean by "main board"?
The board the regulator is powering, like a DAC for instance?
There are input/output caps on the regulator module, so the ground pin of the 3 terminal connection will carry AC currents from the PSU ripple and load current,. This will corrupt the ground reference, and the performance of this regulator will not be better than a LM317 (it could actually be worse), unless the load draws a constant current and the incoming power supply is already very well filtered, in which case, one has to wonder why using an expensive regulator with such high PSRR and low noise...
Yes. Decoupling caps are always located electrically close to the load... the inductance of a properly mounted hand-solderable SMD ceramic is lower than 1nH. The black-box POSCAPs that Coris used, again when properly mounted, are about 1.5 to 2.5 nH, that's equivalent to a wire loop of about 1 to 1.5 mm2 area... putting them on a daughterboard with a 3 pin connection will add 10-50x more inductance, it is a waste of a good capacitor, you could use a noname electrolytic, the load wouldn't see any difference.
The regulator module should only have the reference bypass caps, so that almost no current flows in the ground pin. If this makes the regulator unstable, you need shorter connections.
If you want to extract the full performance of this reg while putting it on a daughterboard, you will need at least 2 ground pins, one for current and one for sensing. 2 output pins (current and sense) are also a plus.
Peufeu, thanks
the more I learn about electronics the more I'm sure I should stick to carpentry 🙂
the more I learn about electronics the more I'm sure I should stick to carpentry 🙂
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