Forums

SMPS +/-5V about +50V supply.

Started by Clive Arthur October 9, 2019
I want a switch mode PSU which will give me two ~2A outputs at 5V above 
and below a nominal +50V (say +40V to +60V) DC supply, ie +55V and +45V 
from +50V.

I can probably work out some fairly clunky ways of doing this, but it 
seems possible that there's some topology particularly suited to this 
type of thing.

Any thoughts?

Cheers
-- 
Clive
Clive Arthur wrote...
> > I want a switch mode PSU which will give me two ~2A > outputs at 5V above and below a nominal +50V (say > +40V to +60V) DC supply, ie +55V and +45V from +50V.
I'm a big fan of DC-DC converter modules; two isolated 10-watt regulated 5V modules would do the job. If you want to roll your own dc-dc converter, use a standard transformer type, rather than something inductor based. -- Thanks, - Win
On 09/10/2019 13:38, Winfield Hill wrote:
> Clive Arthur wrote... >> >> I want a switch mode PSU which will give me two ~2A >> outputs at 5V above and below a nominal +50V (say >> +40V to +60V) DC supply, ie +55V and +45V from +50V. > > I'm a big fan of DC-DC converter modules; two isolated > 10-watt regulated 5V modules would do the job. If you > want to roll your own dc-dc converter, use a standard > transformer type, rather than something inductor based.
Thanks, Win. I like the COTS modules too, but this has to be hand-rolled to work at 180'C. I should have mentioned that. Cheers -- Clive
You signed up to work in a oil drilling hole? I hope you are getting paid by the hour
On Wed, 9 Oct 2019 14:48:36 +0100, Clive Arthur
<cliveta@nowaytoday.co.uk> wrote:

>On 09/10/2019 13:38, Winfield Hill wrote: >> Clive Arthur wrote... >>> >>> I want a switch mode PSU which will give me two ~2A >>> outputs at 5V above and below a nominal +50V (say >>> +40V to +60V) DC supply, ie +55V and +45V from +50V. >> >> I'm a big fan of DC-DC converter modules; two isolated >> 10-watt regulated 5V modules would do the job. If you >> want to roll your own dc-dc converter, use a standard >> transformer type, rather than something inductor based. > >Thanks, Win. > >I like the COTS modules too, but this has to be hand-rolled to work at >180'C. I should have mentioned that. > >Cheers
Do the 5 volt offsets need to be regulated? Here are some old open-loop rail boosters. https://www.dropbox.com/sh/qc9dim5h5k4x6f6/AABGpa6X0xQJfNB_H3lkVIUXa?dl=0 -- John Larkin Highland Technology, Inc lunatic fringe electronics
jlarkin@highlandsniptechnology.com wrote...
> > On Wed, 9 Oct 2019, Clive Arthur wrote: >>> Clive Arthur wrote... >>>> >>>> I want a switch mode PSU which will give me two ~2A >>>> outputs at 5V above and below a nominal +50V (say >>>> +40V to +60V) DC supply, ie +55V and +45V from +50V. > > Do the 5 volt offsets need to be regulated?
I like to use coupled inductors. They're available in triple and quad-winding versions. You regulate the output of one secondary, and the other two can go along for the ride, good to maybe 5%, or 10% if there are extremely unbalanced currents. I'd buck a 5-volt supply from 50V to start the process; and run transformer near 50% for good 20W efficiency. -- Thanks, - Win
On 09/10/2019 16:27, Winfield Hill wrote:
> jlarkin@highlandsniptechnology.com wrote... >> >> On Wed, 9 Oct 2019, Clive Arthur wrote: >>>> Clive Arthur wrote... >>>>> >>>>> I want a switch mode PSU which will give me two ~2A >>>>> outputs at 5V above and below a nominal +50V (say >>>>> +40V to +60V) DC supply, ie +55V and +45V from +50V. >> >> Do the 5 volt offsets need to be regulated? > > I like to use coupled inductors. They're available > in triple and quad-winding versions. You regulate > the output of one secondary, and the other two can > go along for the ride, good to maybe 5%, or 10% if > there are extremely unbalanced currents. I'd buck > a 5-volt supply from 50V to start the process; and > run transformer near 50% for good 20W efficiency. > >
Thanks. I could use a ground referenced 5V too, so that sounds like a buck converter with two extra 5V windings for the 50V +/-5V supplies. Regulation on those isn't critical, so that looks like a winner. The cheque's in the post. Cheers -- Clive
Clive Arthur wrote...
> >On 09/10/2019 16:27, Winfield Hill wrote: >> jlarkin@highlandsniptechnology.com wrote... >>> >>> On Wed, 9 Oct 2019, Clive Arthur wrote: >>>>> Clive Arthur wrote... >>>>>> >>>>>> I want a switch mode PSU which will give me two ~2A >>>>>> outputs at 5V above and below a nominal +50V (say >>>>>> +40V to +60V) DC supply, ie +55V and +45V from +50V. >>> >>> Do the 5 volt offsets need to be regulated? >> >> I like to use coupled inductors. They're available >> in triple and quad-winding versions. You regulate >> the output of one secondary, and the other two can >> go along for the ride, good to maybe 5%, or 10% if >> there are extremely unbalanced currents. I'd buck >> a 5-volt supply from 50V to start the process; and >> run transformer near 50% for good 20W efficiency. > > I could use a ground referenced 5V too, so that sounds > like a buck converter with two extra 5V windings ...
I didn't suggest a single stage converter, because you wanted 10W from each extra 5V output. A 20W 50V to 5V buck is a bit of a beast on its own, needing 4A output, and hence it's switching 4A at 50V for 10% of the time. It needs its own special inductor, especially at 180C. Then you can use a standard coupled inductor, running at 50% to make an efficient isolated dual 5V 2A outputs. -- Thanks, - Win