Design resources for Opamp Mosfet pass regulators

[Zero Cool]

Are there any good magazine articles or design resources for designing Opamp based regulators using Mosfets as pass elements?

 

[duncan2]

Do you mean this sort of thing-


operational amplifier - Op amp voltage regulator using N-Mosfet - Electrical Engineering Stack Exchange

 

[Zero Cool]

yes similar.

 

[Indiglo]

See the attached Maxim Integrated application note for some ideas.

 

[Zero Cool]

this website has some excellent history of the Sulzer regulator. but it uses Bipolar devices. all the web sites and designs i can find on the subject use BJT's. I am trying to find some designs that use a Mosfet Pass element.
Op-Amp Based Linear Regulators

 

[Indiglo]

Here is a mosfet series pass regulator I came across that's from a Audio Research Corporation D240MKII Amplifier manual. See attached. Also included parts list and component values.

 

[Zero Cool]

Yes the ARC version of a Sulzer regulator is what got me interested in studying them, I noticed they use mosfets and everyone else seems to use Bipolar Pass transistors. But I cannot find any articles on designing them. I can copy a circuit, but I am looking for knowledge into the design aspects of them.

 

[stormsonic]

this website has some excellent history of the Sulzer regulator. but it uses Bipolar devices. all the web sites and designs i can find on the subject use BJT's. I am trying to find some designs that use a Mosfet Pass element.
Op-Amp Based Linear Regulators

@Zero Cool
Tangentsoft.net webpage have excelent examples about development of regulators. What is valid for BJT pass element, is valid for MOSFET pass element. You can always replace NPN with N-MOS and PNP with P-MOS. More important than pass element is choice of opamp used.

You can start studying excelent work of Walt Jung.

What are your design choices for MOSFET pass element? Higher treshold voltage, plenty of MOSFETS available at your drawer,.....?

 

[duncan2]

JLH,s first regulated power supply for the 1984 -80 watt design featured a MJ xxx pass BJT ( TO3 ) it soon became apparent to me ( after two replacements ) -JLH and other builders that it didn't take much to blow it.


He then quickly redesigned it for a high power mosfet ( both channels ) ,that cured the over-sensitivity of the BJT to blow under the least provocation.


Schematics should be available online ---he did ( as usual ) get a lot of flack from DS who is a strong advocate of a simple power supply having the ability to provide vast quantities of current immediately .


Whether he has changed his attitude I do not know as I stopped buying EW/WW once the "Audio Era " of EW/WW was over ( and a new editor ) installed.

 

[duncan2]

This was the earlier (susceptible to blowing the pass BJT,s)-


ETI7-84a.gif (GIF Image, 1034 × 821 pixels) – Scaled (96%)


And this is the later revised and stable mosfet version -


ETI5-89a.gif (GIF Image, 977 × 1077 pixels) – Scaled (91%)