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Re: Achieving 98% efficiency in a boost converter, inducement

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  Re: Achieving 98% efficiency in a boost converter, inducement Winfield Hill <hill@rowland.harvard.edu> - 2017-03-09 07:21 -0800
    Re: Achieving 98% efficiency in a boost converter, inducement Winfield Hill <hill@rowland.harvard.edu> - 2017-03-09 08:29 -0800
      Re: Achieving 98% efficiency in a boost converter, inducement Don Kuenz <g@crcomp.net> - 2017-03-09 21:30 +0000
        Re: Achieving 98% efficiency in a boost converter, inducement Winfield Hill <hill@rowland.harvard.edu> - 2017-03-09 13:59 -0800
          Re: Achieving 98% efficiency in a boost converter, inducement Winfield Hill <hill@rowland.harvard.edu> - 2017-03-10 05:30 -0800
      Re: Achieving 98% efficiency in a boost converter, deadline Winfield Hill <hill@rowland.harvard.edu> - 2017-03-10 05:34 -0800
        Re: Achieving 98% efficiency in a boost converter, deadline sea moss <danluster81@gmail.com> - 2017-03-10 21:10 -0800
          Re: Achieving 98% efficiency in a boost converter, deadline Winfield Hill <hill@rowland.harvard.edu> - 2017-03-11 05:40 -0800
            Re: Achieving 98% efficiency in a boost converter, RIS-767, new 11-page document Winfield Hill <hill@rowland.harvard.edu> - 2017-03-16 07:55 -0700
    Re: Achieving 98% efficiency in a boost converter, inducement Joerg <news@analogconsultants.com> - 2017-03-16 08:08 -0700
      Re: Achieving 98% efficiency in a boost converter, inducement Winfield Hill <hill@rowland.harvard.edu> - 2017-03-16 08:54 -0700
        Re: Achieving 98% efficiency in a boost converter, inducement Joerg <news@analogconsultants.com> - 2017-03-16 09:36 -0700
          Re: Achieving 98% efficiency in a boost converter, inducement Winfield Hill <hill@rowland.harvard.edu> - 2017-03-16 10:42 -0700
            Re: Achieving 98% efficiency in a boost converter, inducement legg <legg@nospam.magma.ca> - 2017-03-19 17:58 -0400
              Re: Achieving 98% efficiency in a boost converter, RIS-767 Winfield Hill <hill@rowland.harvard.edu> - 2017-03-19 15:38 -0700
                Re: Achieving 98% efficiency in a boost converter, RIS-767 legg <legg@nospam.magma.ca> - 2017-03-22 21:49 -0400
                Re: Achieving 98% efficiency in a boost converter, RIS-767 legg <legg@nospam.magma.ca> - 2017-04-12 11:52 -0400
                  Re: Achieving 98% efficiency in a boost converter, RIS-767 Winfield Hill <hill@rowland.harvard.edu> - 2017-04-12 10:12 -0700
                    Re: Achieving 98% efficiency in a boost converter, RIS-767 Joerg <news@analogconsultants.com> - 2017-04-12 10:26 -0700
                      Re: Achieving 98% efficiency in a boost converter, RIS-767 legg <legg@nospam.magma.ca> - 2017-04-12 17:24 -0400
                        Re: Achieving 98% efficiency in a boost converter, RIS-767 Joerg <news@analogconsultants.com> - 2017-04-13 07:13 -0700
                    Re: Achieving 98% efficiency in a boost converter, RIS-767 Winfield Hill <hill@rowland.harvard.edu> - 2017-04-12 10:29 -0700
                      Re: Achieving 98% efficiency in a boost converter, RIS-767 legg <legg@nospam.magma.ca> - 2017-04-12 17:07 -0400
                        Re: Achieving 98% efficiency in a boost converter, RIS-767 Winfield Hill <hill@rowland.harvard.edu> - 2017-04-13 08:22 -0700
                          Re: Achieving 98% efficiency in a boost converter, RIS-767 legg <legg@nospam.magma.ca> - 2017-04-22 16:58 -0400
                          Re: Achieving 98% efficiency in a boost converter, RIS-767 Winfield Hill <hill@rowland.harvard.edu> - 2017-05-01 15:08 -0700
                            Re: Achieving 98% efficiency in a boost converter, RIS-767 Winfield Hill <hill@rowland.harvard.edu> - 2017-05-05 13:27 -0700
                              Re: Achieving 98% efficiency in a boost converter, RIS-767 Don Kuenz <g@crcomp.net> - 2017-05-06 05:31 +0000
                            Re: Achieving 98% efficiency in a boost converter, RIS-767 dagmargoodboat@yahoo.com - 2017-05-07 14:49 -0700
                              Re: Achieving 98% efficiency in a boost converter, RIS-767 Winfield Hill <hill@rowland.harvard.edu> - 2017-05-08 12:05 -0700
                                Re: Achieving 98% efficiency in a boost converter, RIS-767 sea moss <danluster81@gmail.com> - 2017-05-08 18:50 -0700
                                  Re: Achieving 98% efficiency in a boost converter, RIS-767 Winfield Hill <hill@rowland.harvard.edu> - 2017-05-08 19:27 -0700
    Re: Achieving 98% efficiency in a boost converter, inducement George Herold <gherold@teachspin.com> - 2017-03-22 19:38 -0700

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#456008 — Re: Achieving 98% efficiency in a boost converter, RIS-767

On 2017-04-12 14:24, legg wrote:
> On Wed, 12 Apr 2017 10:26:03 -0700, Joerg <news@analogconsultants.com>
> wrote:
>
>> On 2017-04-12 10:12, Winfield Hill wrote:
> <snip>
>>>    Another big part is the MOSFET's tradoff, for
>>>    Ron and Coss.  Low Ron goes along with high
>>>    Coss, and thus high C V^2 f losses.
>>>
>>
>> This may be one of the rare occasions where GaN FETs might make sense.
>
> something like EPC2014 offers 16mR with total gate charge of 2nC.
> only 1/3 of that is Qgs.
>
> The trouble would be getting it to run at 600mV.
>

You need a helper converter to make a few volts at very low current. If 
it is a requirement to start at <600mV one could use a JFET for that.


> At least in this app, there are no heatsink considerations.
>

:-)

-- 
Regards, Joerg

http://www.analogconsultants.com/

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#455918 — Re: Achieving 98% efficiency in a boost converter, RIS-767

Winfield Hill wrote...
>
> legg wrote...
>> Winfield Hill wrote:
>>>legg wrote...
>>>>
>>>> Scaling assumptions that approach an order
>>>> of magnitude are often troublesome.  Two
>>>> orders of magnitude will require more than
>>>> just serious thought.
>>>
>>> Yes, right.  And also bench experimenting.
>>> Hence my offer for free RIS-767 boards.
>>
>> What's the solar cell source unloaded output
>> voltage?  With 600mV loaded, I'd expect >900mV?
>> If so,
>>
>>https://datasheets.maximintegrated.com/en/ds/MAX17220-MAX17225.pdf
>
> Right.  Quite a few boost converters claim to
> achieve 95% under certain circumstances. 
> I purchased eval boards for about 10 of them,
> but wasn't able to get better than 90% for my
> 2.0 to 2.4-volt boost.  One did 92-94% at 25mW 
> with 0.8 volts in, but strangely deteriorated
> at 2.0 volts in.  In many cases it appeared the
> eval board inductors were too small.  First,
> too low a value, and second, too much core loss.
> It seems the manufacturers just want to prove
> how small their overall used space will be.
> 
> So I have footprints for about a dozen inductor
> types.  I also wound an RM8-core inductor, that
> measured to fit into a 98% budget (next post),
> so I think that part of the scene is possible.  

 From the 2nd-page of my document on DropBox:
 "98% goal: I picked an input of 0.6V.  That’s a
 single solar cell’s voltage, and a harder test
 case.  We’ll try to achieve 98% efficiency with
 600mV input and 2.4V output at 10mA load = 24mW.
 Boost converter freq 250kHz.  An RM8 inductor,
 with a low-loss 100uH winding, can work well.
 Measured DCR 0.018 Ω for 0.03mW calculated loss,
 and AC res 1.3 Ω, for 0.06mW loss.  TS3A24159
 CMOS switch, Vcc = 3.3V, for Ron 0.10 Ω, loss
 0.16mW.  Switching 2.4V with its Coss=150pF,
 loss 0.21mW.  This gives a calculated continuous
 loss of 0.46mW, which is 2% of 24mW."

 To compare the MAX1721: Ron 0.06 and 0.15 ohms.
 The switching capacitance isn't given.  With an
 efficient inductor could be a winner.  I haven't
 the new rev of the board yet, maybe I can add it.


-- 
 Thanks,
    - Win

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#455943 — Re: Achieving 98% efficiency in a boost converter, RIS-767

On 12 Apr 2017 10:29:45 -0700, Winfield Hill
<hill@rowland.harvard.edu> wrote:

>Winfield Hill wrote...
>>
>> legg wrote...
>>> Winfield Hill wrote:
>>>>legg wrote...
>>>>>
>>>>> Scaling assumptions that approach an order
>>>>> of magnitude are often troublesome.  Two
>>>>> orders of magnitude will require more than
>>>>> just serious thought.
>>>>
>>>> Yes, right.  And also bench experimenting.
>>>> Hence my offer for free RIS-767 boards.
>>>
>>> What's the solar cell source unloaded output
>>> voltage?  With 600mV loaded, I'd expect >900mV?
>>> If so,
>>>
>>>https://datasheets.maximintegrated.com/en/ds/MAX17220-MAX17225.pdf
>>
>> Right.  Quite a few boost converters claim to
>> achieve 95% under certain circumstances. 
>> I purchased eval boards for about 10 of them,
>> but wasn't able to get better than 90% for my
>> 2.0 to 2.4-volt boost.  One did 92-94% at 25mW 
>> with 0.8 volts in, but strangely deteriorated
>> at 2.0 volts in.  In many cases it appeared the
>> eval board inductors were too small.  First,
>> too low a value, and second, too much core loss.
>> It seems the manufacturers just want to prove
>> how small their overall used space will be.
>> 
>> So I have footprints for about a dozen inductor
>> types.  I also wound an RM8-core inductor, that
>> measured to fit into a 98% budget (next post),
>> so I think that part of the scene is possible.  
>
> From the 2nd-page of my document on DropBox:
> "98% goal: I picked an input of 0.6V.  That’s a
> single solar cell’s voltage, and a harder test
> case.  We’ll try to achieve 98% efficiency with
> 600mV input and 2.4V output at 10mA load = 24mW.
> Boost converter freq 250kHz.  An RM8 inductor,
> with a low-loss 100uH winding, can work well.
> Measured DCR 0.018 &#8486; for 0.03mW calculated loss,
> and AC res 1.3 &#8486;, for 0.06mW loss.  TS3A24159
> CMOS switch, Vcc = 3.3V, for Ron 0.10 &#8486;, loss
> 0.16mW.  Switching 2.4V with its Coss=150pF,
> loss 0.21mW.  This gives a calculated continuous
> loss of 0.46mW, which is 2% of 24mW."
>
> To compare the MAX1721: Ron 0.06 and 0.15 ohms.
> The switching capacitance isn't given.  With an
> efficient inductor could be a winner.  I haven't
> the new rev of the board yet, maybe I can add it.

The 17224/5 switches are 31 and 75mR typ.

When 10mA load current was plugged into their EEsim tool, it spat out
a 10mR 10uH inductor, but the sim doesn't function for inputs below
950mV, if it functions at all (I couldn't get anything sensible).

There's a dev board with a 'buy' button in the GUI that is
non-functional. It's photo shows the kind of crap inductor expected.

It wouldn't be possible to separate the control cct losses, but
internal start-up load is supposed to look like 3KR. This load
condition is off their efficiency charts, but most non-isolated
commercial applications consider anything over 90% to be creditable.

I don't know if you've noticed, but the 8pin bobbin for RM8 is no
longer offered by the usual vendors. There's a Polish source on EBay.

The kit here is gathering dust......

RL

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#456010 — Re: Achieving 98% efficiency in a boost converter, RIS-767

legg wrote...
>
> The 17224/5 switches are 31 and 75mR typ.

 Yes, but with higher Coss losses.  But I like the highly
 effective variable switching frequency scheme.  But they
 are offering a family, which makes them more attractive.

> The kit here is gathering dust......

 Yep.  OK, I thought to replace U13, the TPS61070, with
 the MAX1722x family, but the uDFN package is so small,
 I was able to shove some things around and add it as
 an additional selection.  I managed to find room for
 one more 0805 1% resistor, to set the output voltage.

 It's time for me to go ahead and order the PCB now.


-- 
 Thanks,
    - Win

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#457365 — Re: Achieving 98% efficiency in a boost converter, RIS-767

On 13 Apr 2017 08:22:42 -0700, Winfield Hill
<hill@rowland.harvard.edu> wrote:

>legg wrote...
>>
>> The 17224/5 switches are 31 and 75mR typ.
>
> Yes, but with higher Coss losses.  But I like the highly
> effective variable switching frequency scheme.  But they
> are offering a family, which makes them more attractive.
>
>> The kit here is gathering dust......
>
> Yep.  OK, I thought to replace U13, the TPS61070, with
> the MAX1722x family, but the uDFN package is so small,
> I was able to shove some things around and add it as
> an additional selection.  I managed to find room for
> one more 0805 1% resistor, to set the output voltage.
>
> It's time for me to go ahead and order the PCB now.

It looks like MAX17222 is the only actual part you can buy, at the
moment (digikey zero stock but short leadtime). 

A sales rep followed up on the funny EE-Sim performance, with no
knowledge of the original query. I mentioned your project, but didn't
try to button-hole him on availability of samples of the other
flavours.

RL

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#458282 — Re: Achieving 98% efficiency in a boost converter, RIS-767

Winfield Hill wrote...
>
> legg wrote...
>>
>> The 17224/5 switches are 31 and 75mR typ.
>
> Yes, but with higher Coss losses.  But I like the highly
> effective variable switching frequency scheme.  But they
> are offering a family, which makes them more attractive.
>
>> The kit here is gathering dust......
>
> Yep.  OK, I thought to replace U13, the TPS61070, with
> the MAX1722x family, but the uDFN package is so small,
> I was able to shove some things around and add it as
> an additional selection.  I managed to find room for
> one more 0805 1% resistor, to set the output voltage.
>
> It's time for me to go ahead and order the PCB now.

 The boards have arrived. I sent Rob Legg his set, next
 I'll send Don Kuenz his pair, and check my email for
 sea moss' mailing address.  I'm not sure, but I think
 James Arthur is out, too busy.  Did anyone I missed
 opt for one?  Any other new customers?

 The RIS-767 files have been updated: Now there's more
 discussion, top and bottom pcb-traces, 2-side assembly
 drawings, plus the orginal four example versions.  The
 DropBox folder now includes Altium CAD files + Gerber.
 https://www.dropbox.com/sh/6dnpm6muic6st2c/AACSpd3gJEjWT1SYyxS_wutga?dl=0


-- 
 Thanks,
    - Win

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#458975 — Re: Achieving 98% efficiency in a boost converter, RIS-767

Winfield Hill wrote...
>
> The boards have arrived. I sent Rob Legg his set, next
> I'll send Don Kuenz his pair, and check my email for
> sea moss' mailing address.  I'm not sure, but I think
> James Arthur is out, too busy.  Did anyone I missed
> opt for one?  Any other new customers?

 OK, Don, your set of boards is on the way.  I chopped
 up one set of 20 flip-chip daughterboards, you can use
 your fancy saw for the other set.

> The RIS-767 files have been updated: Now there's more
> discussion, top and bottom pcb-traces, 2-side assembly
> drawings, plus the orginal four example versions.  The
> DropBox folder now includes Altium CAD files + Gerber.
> https://www.dropbox.com/sh/6dnpm6muic6st2c/AACSpd3gJEjWT1SYyxS_wutga?dl=0

 I've added searchable parts-location assembly drawings.


-- 
 Thanks,
    - Win

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#459044 — Re: Achieving 98% efficiency in a boost converter, RIS-767

Winfield Hill <hill@rowland.harvard.edu> wrote:
> Winfield Hill wrote...
>>
>> The boards have arrived. I sent Rob Legg his set, next
>> I'll send Don Kuenz his pair, and check my email for
>> sea moss' mailing address.  I'm not sure, but I think
>> James Arthur is out, too busy.  Did anyone I missed
>> opt for one?  Any other new customers?
>
> OK, Don, your set of boards is on the way.  I chopped
> up one set of 20 flip-chip daughterboards, you can use
> your fancy saw for the other set.
>
>> The RIS-767 files have been updated: Now there's more
>> discussion, top and bottom pcb-traces, 2-side assembly
>> drawings, plus the orginal four example versions.  The
>> DropBox folder now includes Altium CAD files + Gerber.
>> https://www.dropbox.com/sh/6dnpm6muic6st2c/AACSpd3gJEjWT1SYyxS_wutga?dl=0
>
> I've added searchable parts-location assembly drawings.

My metal circular saw blade works great with sheet metal. FR4 may
require an abrasive blade to keep the FR4 from splintering. :0)

Thank you,

--
Don Kuenz KB7RPU

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#459309 — Re: Achieving 98% efficiency in a boost converter, RIS-767

On Monday, May 1, 2017 at 6:08:34 PM UTC-4, Winfield Hill wrote:

>  The boards have arrived. I sent Rob Legg his set, next
>  I'll send Don Kuenz his pair, and check my email for
>  sea moss' mailing address.  I'm not sure, but I think
>  James Arthur is out, too busy.

Yep, too busy, but thanks Win.

Cheers,
James Arthur

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#459415 — Re: Achieving 98% efficiency in a boost converter, RIS-767

dagmargoodboat@yahoo.com wrote...
>
> On May 1, 2017, Winfield Hill wrote:
>
>>  The boards have arrived. I sent Rob Legg his set, next
>>  I'll send Don Kuenz his pair, and check my email for
>>  sea moss' mailing address.  I'm not sure, but I think
>>  James Arthur is out, too busy.
>
> Yep, too busy, but thanks Win.

 Yep.

 Dan, your RIS-767 with 20 chopped-up flip-chip
 daughterboards is on its way.


-- 
 Thanks,
    - Win

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#459484 — Re: Achieving 98% efficiency in a boost converter, RIS-767

Great.  Thanks for taking the time to chop up the boards.  I forgot to ask what the required tolerance is on the 2.4V output... how about 10%, too loose?

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#459489 — Re: Achieving 98% efficiency in a boost converter, RIS-767

sea moss wrote...
>
>Great.  Thanks for taking the time to chop up the boards.  I forgot to ask what
>the required tolerance is on the 2.4V output... how about 10%, too loose?

No, of course not.  My idea for these test-bench boards is that you set your own
criteria and experiment away!  Have fun, let us know what you learn.


-- 
 Thanks,
    - Win

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#453174

On Thursday, March 9, 2017 at 10:21:22 AM UTC-5, Winfield Hill wrote:
> Winfield Hill wrote...
> >
> > dagmargoodboat@yahoo.com wrote...
> >>
> >> On November 9, 2016 at 6:54:04 PM UTC-5, Winfield Hill wrote:
> >>> Anybody care to speculate about the most important aspects to consider
> >>> when trying to achieve 98% efficiency in a low-power (20mW) boost
> >>> converter?  Most available step-up converter circuits seem to perform
> >>> in the 85 to 90% region.
> >>> 
> >>> I'm finishing a PCB "test bed" layout, which allows jumper-selection
> >>> of different inductors, synchronous switches, and adjustable controller
> >>> parameters.  I'm hoping not to forget something important before
> >>> sending it off to the PCB house.  Just for fun I thought I'd make it
> >>> in the form of an Arduino shield; giving an option for the processor
> >>> to control the parameters and take measurements.
> >>
> >> Too many degrees of freedom to answer you Win [ snip ]
> >
> > Thanks, your comments are right on target and can kick
> > off the discussion I was hoping to see.  I'll get into
> > that conversation tomorrow.  But in the meantime I've
> > updated my draft schematic and PCB layout, adding more
> > features and items relevant to the discussion.
> >
> > Here's an inducement: anyone who'd like to experiment
> > with issues and concepts embedded in the RIS-767
> > board, I'll send you two blank PCBs to play with.
> > You just have to talk about what you learn, should
> > you get around to learning anything!
> 
>  The design has been updated and is ready to order.
> https://www.dropbox.com/s/hhl1mwq7mjeo622/RIS-767_b_sch%2Blayouy-pics.pdf?dl=0
> 
>  Here's what my document says, achieving a 98% result:
>  One test condition: 600mV input from a solar cell,
>  2.4V out at 10mA load = 24mW.  Boost converter 
>  operation at 250kHz.  Critical for success: an RM8
>  inductor, low-loss winding, measured DCR 0.018 Ω,
>  calculated loss 0.03mW, and AC loss 1.3 Ω, 0.06mW.
>  Best estimated CMOS switch, TS3A24159 powered from
>  Vcc = 3.3V. Ron 0.10 Ω, loss 0.16mW.  Calculated
>  switch loss, switching 2.4V with Coss=150pF, 0.21mW.
> 
>  Continuous total loss 0.46mW = 2% of 24mW (not
>  counting 0.18mW in sense resistors).
> 
>  I had only one email about a free PCB, but with no
>  followup to my answer.  My offer still stands.
Thanks, Win.. I've been ordering all sorts of PCB's 
(in lot's of 2) from advanced circuits.
(for ~$75*, it's cheap to have them check my layout,
(mostly uncertainty that I got the mechanicals right.))   
They're piling up in my drawer.  If people would stop
ordering things from us, I could get to them... :^)

George H. 

> 
> -- 
>  Thanks,
>     - Win

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