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inverting switcher

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

I can do this

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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.

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John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin
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So get one that's sync rect with a force-CCM option.

Tim

-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website:

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Reply to
Tim Williams

On a sunny day (Mon, 25 Nov 2019 16:40:55 -0800) it happened John Larkin wrote in :

If it is a wallwart just reverse the + and - coming from it and use a normal circuit? :=)

Reply to
Jan Panteltje

Sounds like low current

Why not a switched capacitor solution?

Reply to
Klaus Kragelund

I'd need maybe five wall warts. That might work.

Actually, there are very few negative-to-negative switching regulators around.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
jlarkin

I need voltage conversion and fairly high currents, which charge pumps aren't very good for. And they tend to be spikey noisy.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
jlarkin

Or use an AC wall wart.

Cheers

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Clive
Reply to
Clive Arthur

On a sunny day (Tue, 26 Nov 2019 07:09:43 -0800) it happened snipped-for-privacy@highlandsniptechnology.com wrote in :

No, I should have put it better, something like this:

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Yes for more than one voltage not so easy.

Reply to
Jan Panteltje

On a sunny day (Tue, 26 Nov 2019 15:49:03 GMT) it happened Jan Panteltje wrote in :

oops zener in wrong legg

:-)

Reply to
Jan Panteltje

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:

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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.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
jlarkin

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

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
jlarkin

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
Reply to
John Larkin

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

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Reply to
Dimiter_Popoff

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

Best regards, Piotr

Reply to
Piotr Wyderski

How much current? For ~$5(?10?) you can get three pin switchers that can go negative ~100mA.

George H.

Reply to
George Herold

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