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Monolithic DC/DC converters

Discussion in 'Embedded' started by Benjamin Couillard, Oct 7, 2011.

  1. 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
    Benjamin Couillard, Oct 7, 2011
    #1
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  2. Benjamin Couillard

    Tim Wescott Guest

    On Fri, 07 Oct 2011 06:12:35 -0700, Benjamin Couillard wrote:

    > 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.


    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.

    --
    www.wescottdesign.com
    Tim Wescott, Oct 7, 2011
    #2
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  3. Benjamin Couillard

    Nico Coesel Guest

    Benjamin Couillard <> wrote:

    >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.


    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.

    --
    Failure does not prove something is impossible, failure simply
    indicates you are not using the right tools...
    nico@nctdevpuntnl (punt=.)
    --------------------------------------------------------------
    Nico Coesel, Oct 7, 2011
    #3
  4. Benjamin Couillard

    Guest

    On Fri, 07 Oct 2011 16:30:42 GMT, (Nico Coesel) wrote:

    >Benjamin Couillard <> wrote:
    >
    >>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.


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

    >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.


    ....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.
    , Oct 7, 2011
    #4
  5. Benjamin Couillard

    steve Guest

    On Oct 7, 9:12 am, Benjamin Couillard <>
    wrote:
    > 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


    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.
    steve, Oct 7, 2011
    #5
  6. Benjamin Couillard

    John Larkin Guest

    On Fri, 7 Oct 2011 06:12:35 -0700 (PDT), Benjamin Couillard
    <> wrote:

    >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


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

    John
    John Larkin, Oct 7, 2011
    #6
  7. Benjamin Couillard

    Tim Wescott Guest

    On Fri, 07 Oct 2011 10:01:02 -0700, John Larkin wrote:

    > On Fri, 7 Oct 2011 06:12:35 -0700 (PDT), Benjamin Couillard
    > <> wrote:
    >
    >>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

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


    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.

    --
    www.wescottdesign.com
    Tim Wescott, Oct 7, 2011
    #7
  8. Benjamin Couillard

    Guest

    On Fri, 07 Oct 2011 10:01:02 -0700, John Larkin
    <> wrote:

    >On Fri, 7 Oct 2011 06:12:35 -0700 (PDT), Benjamin Couillard
    ><> wrote:
    >
    >>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

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


    Here's one (but I don't think it's what he was referring to ;-).
    http://www.analog.com/en/interface/digital-isolators/adum5000/products/product.html
    , Oct 7, 2011
    #8
  9. Benjamin Couillard

    hamilton Guest

    On 10/7/2011 10:30 AM, Nico Coesel wrote:
    > Benjamin Couillard<> wrote:
    >
    >> 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.

    >
    > 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.
    >

    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
    hamilton, Oct 7, 2011
    #9
  10. Benjamin Couillard

    hamilton Guest

    On 10/7/2011 11:08 AM, zzzzzzzz wrote:
    > On Fri, 07 Oct 2011 10:01:02 -0700, John Larkin
    > <> wrote:
    >
    >> On Fri, 7 Oct 2011 06:12:35 -0700 (PDT), Benjamin Couillard
    >> <> wrote:
    >>
    >>> 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

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

    >
    > Here's one (but I don't think it's what he was referring to ;-).
    > http://www.analog.com/en/interface/digital-isolators/adum5000/products/product.html
    >


    I think this is what the OP is talking about:
    http://media.digikey.com/pdf/Data Sheets/Rohm PDFs/BP5302A,BP5302XA.pdf
    hamilton, Oct 7, 2011
    #10
  11. Benjamin Couillard

    Guest

    On Fri, 07 Oct 2011 11:35:26 -0600, hamilton <> wrote:

    >On 10/7/2011 11:08 AM, zzzzzzzz wrote:
    >> On Fri, 07 Oct 2011 10:01:02 -0700, John Larkin
    >> <> wrote:
    >>
    >>> On Fri, 7 Oct 2011 06:12:35 -0700 (PDT), Benjamin Couillard
    >>> <> wrote:
    >>>
    >>>> 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
    >>>
    >>> What do you mean by "monolithic DC/DC converter"? Got a link to one?

    >>
    >> Here's one (but I don't think it's what he was referring to ;-).
    >> http://www.analog.com/en/interface/digital-isolators/adum5000/products/product.html
    >>

    >
    >I think this is what the OP is talking about:
    >http://media.digikey.com/pdf/Data Sheets/Rohm PDFs/BP5302A,BP5302XA.pdf


    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. ;-)
    , Oct 7, 2011
    #11
  12. Benjamin Couillard, Oct 7, 2011
    #12
  13. Benjamin Couillard

    Rob Gaddi Guest

    On 10/7/2011 1:15 PM, Benjamin Couillard wrote:
    > This is an example what I had in mind
    >
    > http://cds.linear.com/docs/Datasheet/8023fg.pdf
    >
    > The inductor and capacitors are integrated in the package, only a few
    > external components are needed.
    >
    > Thanks for your answers by the way.


    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.

    --
    Rob Gaddi, Highland Technology
    Email address is currently out of order
    Rob Gaddi, Oct 7, 2011
    #13
  14. Benjamin Couillard

    Guest

    On Fri, 07 Oct 2011 14:19:32 -0700, Rob Gaddi <>
    wrote:

    >On 10/7/2011 1:15 PM, Benjamin Couillard wrote:
    >> This is an example what I had in mind
    >>
    >> http://cds.linear.com/docs/Datasheet/8023fg.pdf
    >>
    >> The inductor and capacitors are integrated in the package, only a few
    >> external components are needed.
    >>
    >> Thanks for your answers by the way.

    >
    >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.


    I *GUESS* they're pricey! $16.90 to $34.58 in DigiKey.
    , Oct 7, 2011
    #14
  15. Benjamin Couillard

    Rich Grise Guest

    Tim Wescott wrote:
    > On Fri, 07 Oct 2011 06:12:35 -0700, Benjamin Couillard wrote:
    >>
    >> 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.

    >
    > 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.
    >

    + labor.

    Hope This Helps!
    Rich
    Rich Grise, Oct 7, 2011
    #15
  16. Benjamin Couillard

    Rob Gaddi Guest

    On 10/7/2011 2:51 PM, zzzzzzzz wrote:
    > On Fri, 07 Oct 2011 14:19:32 -0700, Rob Gaddi<>
    > wrote:
    >
    >> On 10/7/2011 1:15 PM, Benjamin Couillard wrote:
    >>> This is an example what I had in mind
    >>>
    >>> http://cds.linear.com/docs/Datasheet/8023fg.pdf
    >>>
    >>> The inductor and capacitors are integrated in the package, only a few
    >>> external components are needed.
    >>>
    >>> Thanks for your answers by the way.

    >>
    >> 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.

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


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

    --
    Rob Gaddi, Highland Technology
    Email address is currently out of order
    Rob Gaddi, Oct 7, 2011
    #16
  17. Benjamin Couillard

    John Larkin Guest

    On Fri, 07 Oct 2011 15:29:37 -0700, Rob Gaddi
    <> wrote:

    >On 10/7/2011 2:51 PM, zzzzzzzz wrote:
    >> On Fri, 07 Oct 2011 14:19:32 -0700, Rob Gaddi<>
    >> wrote:
    >>
    >>> On 10/7/2011 1:15 PM, Benjamin Couillard wrote:
    >>>> This is an example what I had in mind
    >>>>
    >>>> http://cds.linear.com/docs/Datasheet/8023fg.pdf
    >>>>
    >>>> The inductor and capacitors are integrated in the package, only a few
    >>>> external components are needed.
    >>>>
    >>>> Thanks for your answers by the way.
    >>>
    >>> 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.

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

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


    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
    John Larkin, Oct 8, 2011
    #17
  18. Benjamin Couillard

    Chiron613 Guest

    On Fri, 07 Oct 2011 15:29:37 -0700, Rob Gaddi wrote:

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

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



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


    --
    There is no statute of limitations on stupidity.
    Chiron613, Oct 8, 2011
    #18
  19. On Sat, 08 Oct 2011 02:14:11 GMT, the renowned Chiron613
    <> wrote:

    >On Fri, 07 Oct 2011 15:29:37 -0700, Rob Gaddi wrote:
    >
    ><snip>
    >>>
    >>> I *GUESS* they're pricey! $16.90 to $34.58 in DigiKey.

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

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


    L_inear T_echnology Corporat_I_on. (direct sales).

    http://www.linear.com/purchase/


    Best regards,
    Spehro Pefhany
    --
    "it's the network..." "The Journey is the reward"
    Info for manufacturers: http://www.trexon.com
    Embedded software/hardware/analog Info for designers: http://www.speff.com
    Spehro Pefhany, Oct 8, 2011
    #19
  20. Benjamin Couillard

    Chiron613 Guest

    On Fri, 07 Oct 2011 22:33:07 -0400, Spehro Pefhany wrote:

    > On Sat, 08 Oct 2011 02:14:11 GMT, the renowned Chiron613
    > <> wrote:
    >
    >>On Fri, 07 Oct 2011 15:29:37 -0700, Rob Gaddi wrote:
    >>
    >><snip>
    >>>>
    >>>> I *GUESS* they're pricey! $16.90 to $34.58 in DigiKey.
    >>>
    >>> That's insane. Direct from LTI, single piece pricing is about $12.

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

    >
    > L_inear T_echnology Corporat_I_on. (direct sales).
    >
    > http://www.linear.com/purchase/
    >
    >
    > Best regards,
    > Spehro Pefhany


    Many thanks, Sphero...



    --
    Forty two.
    Chiron613, Oct 8, 2011
    #20
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