inverting switcher

On Tue, 26 Nov 2019 15:24:13 +0000, Clive Arthur
<cliveta@nowaytoday.co.uk> wrote:

>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

Universal-input warts are nice, with an international plug adapter
set. And AC would still be a problem, getting multiple voltages of
both polarities.



-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

On Mon, 25 Nov 2019 16:40:55 -0800, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

>
>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.

OK, I want a potted brick with one DC input, 12 or 24 volts, and 5 or
so DC outputs. Each output should be programmable for voltage and
polarity, either resistors or an SPI interface with nonvolatile
memory. 5 or maybe 10 watts.

-- 

John Larkin         Highland Technology, Inc
picosecond timing   precision measurement 

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

On 11/26/2019 2:40, John Larkin wrote:
> 
> 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.
 > ....

Why do you not want it? I am asking because I just discovered its
existence through your post and now I wonder what catch may be there to
prevent me from trying it out (not that I really need it, ltspice is
just OK for me, too).

Dimiter

======================================================
Dimiter Popoff, TGI             http://www.tgi-sci.com
======================================================
http://www.flickr.com/photos/didi_tgi/

John Larkin wrote:

> I have +12 from a wart, and I need -1.2 and -5 to power some analog
> stuff and ECL.

LT3999, LT3439 or IR21531. All depends on your output power 
requirements, noise figure and budget.

	Best regards, Piotr

On Monday, November 25, 2019 at 7:41:05 PM UTC-5, John Larkin wrote:
> I have +12 from a wart, and I need -1.2 and -5 to power some analog
> stuff and ECL.
How much current?  For ~$5(?10?) you can get three pin switchers that 
can go negative ~100mA.

George H. 
> 
> 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