Forums

inverting switcher

Started by John Larkin November 25, 2019
I have +12 from a wart, and I need -1.2 and -5 to power some analog
stuff and ECL.

I can do this

https://www.dropbox.com/s/3b0iff93k1k2ct6/TPS_Inv_1.JPG?raw=1


Problem is, I don't want to run Tina and there is no LT Spice model.

It may go into burp mode at my modest load currents, so I could get a
lot of output ripple. It might want some lead compensation too. I
guess I should breadboard it.

This will be noisy, so maybe I'll put the switchers on the bottom of
the board, and I'd have the ground plane between them and the
jitter-sensitive stuff.

We have MIC4690 in stock. That might be a better choice. Again, no
model.

-- 

John Larkin         Highland Technology, Inc
picosecond timing   precision measurement 

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

So get one that's sync rect with a force-CCM option.

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

"John Larkin" <jlarkin@highland_atwork_technology.com> wrote in message 
news:f1sotedf4ldau7297ql7og02cvjosboihs@4ax.com...
> > I have +12 from a wart, and I need -1.2 and -5 to power some analog > stuff and ECL. > > I can do this > > https://www.dropbox.com/s/3b0iff93k1k2ct6/TPS_Inv_1.JPG?raw=1 > > > Problem is, I don't want to run Tina and there is no LT Spice model. > > It may go into burp mode at my modest load currents, so I could get a > lot of output ripple. It might want some lead compensation too. I > guess I should breadboard it. > > This will be noisy, so maybe I'll put the switchers on the bottom of > the board, and I'd have the ground plane between them and the > jitter-sensitive stuff. > > We have MIC4690 in stock. That might be a better choice. Again, no > model. > > -- > > John Larkin Highland Technology, Inc > picosecond timing precision measurement > > jlarkin att highlandtechnology dott com > http://www.highlandtechnology.com >
On a sunny day (Mon, 25 Nov 2019 16:40:55 -0800) it happened John Larkin
<jlarkin@highland_atwork_technology.com> wrote in
<f1sotedf4ldau7297ql7og02cvjosboihs@4ax.com>:

> >I have +12 from a wart, and I need -1.2 and -5 to power some analog >stuff and ECL.
If it is a wallwart just reverse the + and - coming from it and use a normal circuit? :=)
Sounds like low current

Why not a switched capacitor solution?
On Tue, 26 Nov 2019 08:18:54 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:

>On a sunny day (Mon, 25 Nov 2019 16:40:55 -0800) it happened John Larkin ><jlarkin@highland_atwork_technology.com> wrote in ><f1sotedf4ldau7297ql7og02cvjosboihs@4ax.com>: > >> >>I have +12 from a wart, and I need -1.2 and -5 to power some analog >>stuff and ECL. > >If it is a wallwart just reverse the + and - coming from it and use a normal circuit? > >:=)
I'd need maybe five wall warts. That might work. Actually, there are very few negative-to-negative switching regulators around. -- John Larkin Highland Technology, Inc lunatic fringe electronics
On Tue, 26 Nov 2019 00:57:20 -0800 (PST), Klaus Kragelund
<klauskvik@hotmail.com> wrote:

>Sounds like low current > >Why not a switched capacitor solution?
I need voltage conversion and fairly high currents, which charge pumps aren't very good for. And they tend to be spikey noisy. -- John Larkin Highland Technology, Inc lunatic fringe electronics
On 26/11/2019 08:18, Jan Panteltje wrote:
> On a sunny day (Mon, 25 Nov 2019 16:40:55 -0800) it happened John Larkin > <jlarkin@highland_atwork_technology.com> wrote in > <f1sotedf4ldau7297ql7og02cvjosboihs@4ax.com>: > >> >> I have +12 from a wart, and I need -1.2 and -5 to power some analog >> stuff and ECL. > > If it is a wallwart just reverse the + and - coming from it and use a normal circuit? > > :=) >
Or use an AC wall wart. Cheers -- Clive
On a sunny day (Tue, 26 Nov 2019 07:09:43 -0800) it happened
jlarkin@highlandsniptechnology.com wrote in
<2vfqtehak6bu7rnvue1q5aejl4qa8sf17c@4ax.com>:

>On Tue, 26 Nov 2019 08:18:54 GMT, Jan Panteltje ><pNaOnStPeAlMtje@yahoo.com> wrote: > >>On a sunny day (Mon, 25 Nov 2019 16:40:55 -0800) it happened John Larkin >><jlarkin@highland_atwork_technology.com> wrote in >><f1sotedf4ldau7297ql7og02cvjosboihs@4ax.com>: >> >>> >>>I have +12 from a wart, and I need -1.2 and -5 to power some analog >>>stuff and ECL. >> >>If it is a wallwart just reverse the + and - coming from it and use a normal circuit? >> >>:=) > >I'd need maybe five wall warts. That might work. > >Actually, there are very few negative-to-negative switching regulators >around.
No, I should have put it better, something like this: http://panteltje.com/pub/wallwart_to_negative_IMG_0249.JPG Yes for more than one voltage not so easy.
On a sunny day (Tue, 26 Nov 2019 15:49:03 GMT) it happened Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote in <qrjhhk$tih$1@dont-email.me>:

>On a sunny day (Tue, 26 Nov 2019 07:09:43 -0800) it happened >jlarkin@highlandsniptechnology.com wrote in ><2vfqtehak6bu7rnvue1q5aejl4qa8sf17c@4ax.com>: > >>On Tue, 26 Nov 2019 08:18:54 GMT, Jan Panteltje >><pNaOnStPeAlMtje@yahoo.com> wrote: >> >>>On a sunny day (Mon, 25 Nov 2019 16:40:55 -0800) it happened John Larkin >>><jlarkin@highland_atwork_technology.com> wrote in >>><f1sotedf4ldau7297ql7og02cvjosboihs@4ax.com>: >>> >>>> >>>>I have +12 from a wart, and I need -1.2 and -5 to power some analog >>>>stuff and ECL. >>> >>>If it is a wallwart just reverse the + and - coming from it and use a normal circuit? >>> >>>:=) >> >>I'd need maybe five wall warts. That might work. >> >>Actually, there are very few negative-to-negative switching regulators >>around. > >No, I should have put it better, something like this: > http://panteltje.com/pub/wallwart_to_negative_IMG_0249.JPG > >Yes for more than one voltage not so easy.
oops zener in wrong legg :-)
On Tue, 26 Nov 2019 15:49:03 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:

>On a sunny day (Tue, 26 Nov 2019 07:09:43 -0800) it happened >jlarkin@highlandsniptechnology.com wrote in ><2vfqtehak6bu7rnvue1q5aejl4qa8sf17c@4ax.com>: > >>On Tue, 26 Nov 2019 08:18:54 GMT, Jan Panteltje >><pNaOnStPeAlMtje@yahoo.com> wrote: >> >>>On a sunny day (Mon, 25 Nov 2019 16:40:55 -0800) it happened John Larkin >>><jlarkin@highland_atwork_technology.com> wrote in >>><f1sotedf4ldau7297ql7og02cvjosboihs@4ax.com>: >>> >>>> >>>>I have +12 from a wart, and I need -1.2 and -5 to power some analog >>>>stuff and ECL. >>> >>>If it is a wallwart just reverse the + and - coming from it and use a normal circuit? >>> >>>:=) >> >>I'd need maybe five wall warts. That might work. >> >>Actually, there are very few negative-to-negative switching regulators >>around. > >No, I should have put it better, something like this: > http://panteltje.com/pub/wallwart_to_negative_IMG_0249.JPG > >Yes for more than one voltage not so easy.
I have one board that has 16 different supply rails. This little one I'm considering would have +12, +5, +4, -1.2, and -5. And one variable from 2.5 to 6 or so. From a 12 volt wart, probably. Both neg supplies would be 100 mA or so. Fast parts are power hogs. In a box this size: http://www.highlandtechnology.com/DSS/J730DS.shtml I'm thinking I have to put the power supplies on the bottom of the board. I can move the board up a bit and have a 0.2" gap below. Manufacturing doesn't mind parts on both sides. -- John Larkin Highland Technology, Inc lunatic fringe electronics