Your pick for best regulator needed for -5V 30mA

[riotubes]

I'd appreciate your input on best regulator to build a -5V supply being used to power an active I/V circuit for DAC.

One's I've googled include LM7905 and AN79L05. Which is best, or is there another preference?

Thanks!

[TerryC]

I doubt there is a significant difference between any of the XX05 3-terminal regulators. I really like Per Anders super regulator boards, but if you must use a drop in replacement, these Dexa regulators look like a good value...

http://www.partsconnexion.com/catalo...onductors.html

[pjpoes]

Are you trying for a drop in replacement for a pre-existing circuit or looking for a chip you can design around?

In my opinion Linear Technologies makes among the best regulators, with a few National Semi and Sanyo's that are also not so bad. I really like the LT1175 and LT1185 if you can design your own regulator board. Their suggested design is pretty good too, not a lot of tweaking needed. Biggest issue with the LT regulators is that most of them are only available in surface mount now a days. However I think you could make a small drop in surface mount to 3 pin as a replacement for a typical 3 pin regulator. Most feel that the adjustable regulators offer better regulation than the non-adjustable fixed regulators that are so common. Having said that, I think you fill find that the design of the circuit will have a greater impact than simple chip selection. Of course they need to be addressed together, a better chip with a better regulator chip will be better, but don't neglect the rest.

[Mooly]

Hi,
For 30 ma I think I would use a shunt regulator rather than series pass.

[MaKari]

Hi

LM337L is still usefull. Please, check National Semic... Data sheet.
With TL431 or LM4041 reference You can do shunt or series regulator (Pass transitor needed). From data sheets You can find some applicaton examples. All are available "DIY compatible" TO-92 package.

[riotubes]

Thanks for the suggestions! This got me thinking about a discrete regulator. This one was suggested (schematic)

http://db.audioasylum.com/cgi/m.mpl?...ed&r=&session=

I have a dumb question in the interest of self-preservation. Preceding this -5V reg board will be a simple bridge rectifier and smoothing cap. Does the + rail of this unreg psu board connect to the V- input or the Ground of the -5V reg board?

Also, in looking at this schematic, I understand that VOUT- lead goes to the -5V input of the analog board it's powering, but what about the other lead (i.e. ground)? Do I also take the output from the GND on the schematic? Does that GND reflect the point at which the ground reference Input and Output land?

[Mooly]

Are you building this into an existing piece of equipment or do you mean you are making your own PSU (transformer/bridge/caps etc)

[AndrewT]

Originally posted by riotubes
Preceding this -5V reg board will be a simple bridge rectifier and smoothing cap. Does the + rail of this unreg psu board connect to the V- input or the Ground of the -5V reg board?

Also, in looking at this schematic, I understand that VOUT- lead goes to the -5V input of the analog board it's powering, but what about the other lead (i.e. ground)? Do I also take the output from the GND on the schematic? Does that GND reflect the point at which the ground reference Input and Output land?

it does not matter.
A separate PSU will be isolated due to the separate secondary winding.
Keep the regulator output flow and return separate until they reach the PCB. Tie the more positive lead to zero volt connection. Tie the more negative lead to the -5V connection.

[riotubes]

Thank you very much Andrew and Mooly! Yes, the whole circuit is new;it was spec'd for me. On the link below, I've drawn in the power rails for the three boards (unreg psu, -5v reg and I/V board) for the -5V. I hope I have interpreted Andrew's feedback correctly, but would appreciate someone double checking this for me. Here's the link to the diagram...Thanks!

http://gallery.audioasylum.com/cgi/u...e=&w=960&h=720

[richie00boy]

Originally posted by Mooly
Hi,
For 30 ma I think I would use a shunt regulator rather than series pass.

Why is that? I didn't believe shunt was inherently lower noise or anything.