Monolithic DC/DC converters

Hi everyone,

I have a question for people who use Monolithic DC/DC converters. Do you think the advantages over discrete DC/DC converters are real? Is efficiency comparable? What about EMI? I'm trying to save real estate on a board and I'm considering changing the DC/DC converter to use monolithic but I don't want to sacrifice efficiency or create EMI problems.

Best regards

Benjamin

Reply to
Benjamin Couillard
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I think the biggest plus with monolithic parts is that you save design time and grief on the manufacturing floor. You slap them on the board, and if something goes "pffft" you point at the manufacturer and say "FIX!".

Then you pay for it, compared to the BOM cost of building one yourself.

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Reply to
Tim Wescott

If it is a mass produced product you should stay discrete but find a more compact solution.

I use monolithic converters if I need isolation or when production batches are small.

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Reply to
Nico Coesel

EMI can be an issue. Anything that ventures outside the enclosure has to be filtered pretty well.

...or time short. These things tend to be rather noisy, too, so that can be a consideration. The biggest problems I've had is radiation via cables. These things (particularly the cheap ones) tend to make that problem worse.

Reply to
krw

It's always better (cheaper) to reuse existing designs, either in house or out of house, assuming the existing design meets or slightly exceeds requirements. Existing designs that are overkill need to be evalated.

Reply to
steve

What do you mean by "monolithic DC/DC converter"? Got a link to one?

John

Reply to
John Larkin

Good point. I was assuming he meant anything that comes manufactured as a module, that you thump into a board as if it were an IC. I've used the ones from TI with the 78xx-compatible pinout, although that was a project that never got beyond the prototype stage.

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Reply to
Tim Wescott

Here's one (but I don't think it's what he was referring to ;-).

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Reply to
krw

It also depends on if the converter is "standard".

We use an LCD Vee generator of -22V.

We can not build a converter cheaper then we can buy, there are just too many out there. Size is not a problem ;-) .

As the OP did not state what his converter is use for, who is to say if DIY is cheaper.

hamilton

Reply to
hamilton

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I think this is what the OP is talking about:

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Reply to
hamilton

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Sure. I've used them. I was just answering John's challenge for a "monolithic DC/DC converter". He knows about the ADI iso-power stuff, too. I was just tweaking him. ;-)

Reply to
krw

This is an example what I had in mind

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The inductor and capacitors are integrated in the package, only a few external components are needed.

Thanks for your answers by the way.

Reply to
Benjamin Couillard

Actually making quite a bit of use of that exact part. They're a bit pricey, but the outputs are beautifully clean and they're certainly easy enough to use. The only note on them is that they're non-synchronous switchers, so you'll see some efficiency hit if you're doing big step-down ratios to low voltages.

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Rob Gaddi, Highland Technology
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Reply to
Rob Gaddi

I *GUESS* they're pricey! $16.90 to $34.58 in DigiKey.

Reply to
krw

  • labor.

Hope This Helps! Rich

Reply to
Rich Grise

That's insane. Direct from LTI, single piece pricing is about $12.

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Rob Gaddi, Highland Technology
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Reply to
Rob Gaddi

MAX says we're paying $9.94.

ftp://jjlarkin.lmi.net/LTM1.jpg

ftp://jjlarkin.lmi.net/LTM2.jpg

ftp://jjlarkin.lmi.net/TEM2_Power.JPG

On that last board, the things near the connector are my home-made current shunts.

National has something similar in DPAK sorts of packages, which would be easier to place and especially rework, if you don't have a lot of surface-mount gear.

John

Reply to
John Larkin

Excuse my ignorance, but what is LTI? I could use a lower-cost source for components...

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Reply to
Chiron613

L_inear T_echnology Corporat_I_on. (direct sales).

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Best regards, Spehro Pefhany

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Reply to
Spehro Pefhany

Many thanks, Sphero...

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Reply to
Chiron613

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