It really makes no sense to make a shunt regulator for 5V / 2A because of the excessive dissipation, which would be at least 10W and more. The problem is the voltage drop on the depletion mosfets, which will certainly be higher than 5V.
I assume that it is a regulator for a DAC or something similar so it would be better to make more regulators for smaller currents and power each load separately. Let's say for 5V/ 130mA a 4-5V voltage drop is enough and the dissipation will be small around 1W.
I hope that for the 5V version you don't use the AD825 as an op amp, an excellent choice is the ADA4897 if you know how to 'tame' it but for a start the AD817 will be great.
You can freely use J1, Q3 and Q4 instead of LM329 and R4, but for 5V you have to remove D9, D8 and D7. Instead of J1, you can also use CCS with two depletion mosfets from your first picture with two BSS139 set to a current of ~5mA.
Some work in relation to my post 3367, transformer was not done right, it emited some noise and now it contain common mode cancelation trought aux -> shield winding. Also pcb have some modifications on booth sides, now gnd layer is canaled to force current trought inline dc filter capacitors. I will let you know the final result.
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In relation to post 3382, some result. J.d. regulators are so sensitive to emi noise that they must not be close to flyback regulators, j.d. it picks up the emi noise and through its output we get this kind of spike on the flyback regulator itself, I've been working on solving the problem on flyback for several days and I barely managed to figure out what it was about, its not a problem of flyback but problem of emi : ) I had noise at the j.d. out and in the same time spike inside flyback Ton time. I hope that when I split this board in half and move one away from the other that it will finally everything falls into place. Please take a look at two pictures, one is at mosfets Ton on flyback and seccond one is noise I had on mini j.d. More results soon : )
only when I put these two pictures one under the other, I figured out what the problem was, emi! Unbelievable is that j.d. puts spike back to the flyback because of emi pickup from the switching noise : )
only when I put these two pictures one under the other, I figured out what the problem was, emi! Unbelievable is that j.d. puts spike back to the flyback because of emi pickup from the switching noise : )
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Its a matter of insecurity management. Suppose the devices from the two different manufacturers are not the same, despite the same data sheet.
But you don't know which of the two is 'better'. By deciding for one or the other, you may get the 'worse' of the two.
Better to buy from different manufacturers then at least you have 50% the best.
Just pulling your leg a bit. Don't worry, they are totally uncritical because of the heavy internal feedback in the circuitry.
Jan
But you don't know which of the two is 'better'. By deciding for one or the other, you may get the 'worse' of the two.
Better to buy from different manufacturers then at least you have 50% the best.
Just pulling your leg a bit. Don't worry, they are totally uncritical because of the heavy internal feedback in the circuitry.
Jan
Just wondering if in picture 2 instead of Q3 and Q4 I can use BC850C and BC860C? Or maybe there is better SMD equivalents?
Sorry I was not clear on that.
I do not suggest that the designer/s need/s to update the BOM.
If first post had the BOM with two or three more columns then those experienced in the art could fill in what substitute worked for them.
I don't mind comparing data sheets but I certainly don't have the knowledge to know what specs are the important ones in a specific design.
I don't know If the forum is technically able to provide fill in sheets but it would be a nice feature for any first page of a thread.
Just dreaming 😉
In the Walt Jung article from post #3331 2N3906 and PN2222A was used. So MMBT2222 and MMBT3906 as SMD should be ok. I want to make GLED431 voltage reference 6.9V for +15V and -15V regulator. For CCS probably BSS169 will be ok?
Do you have a schematic?
I have never had a problem with the ADA4897 in 5V or 3,3V regulators .
For the normal version it will be OK for the high current version it will not, in that case they must have at least 1W of dissipation. BSS159 will be better than BSS169 but it can also be used.