Ultra-low power switching boost converter - in a DIP

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For a hobby project, I've found the perfect part for converting battery  
power to a very low current (2 ma at most) 28V power supply.  And that is  
the Linear Technologies LT8410-1 "Ultralow Power Boost Converter".

The problem is that the only package available is a tiny surface mount  
chip that's 2 x 2 millimeters, which effectively makes it impossible to  
deal with using a soldering iron.

Does anyone know of a solution that would let me use this chip - a  
socket, or some way to solder it?  Or, does anyone know of another part  
that performs similarly but has a more hobby-friendly package option?

Thanks for any suggestions.


Re: Ultra-low power switching boost converter - in a DIP
On Sun, 21 Aug 2016 11:13:07 -0500, Peabody

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LTC3803 is a nice little boost converter in a leaded package. Supply
current is a little higher, and it needs an external fet, 2N7002
maybe.

Or you could design your own circuit.


--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: Ultra-low power switching boost converter - in a DIP
On 22/08/16 03:04, John Larkin wrote:
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Data sheet says it's optimized for high input voltages.
What low voltages have you used it for, and how did it cope?

Clifford Heath.

Re: Ultra-low power switching boost converter - in a DIP
On Mon, 22 Aug 2016 10:29:15 +1000, Clifford Heath

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24 to 1400. Worked great. OP didn't say what his battery voltage is.


--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: Ultra-low power switching boost converter - in a DIP
On 23/08/16 00:52, John Larkin wrote:
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That's your output voltage.
What's the lowest input voltage you've used it with?

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True, but we can assume less than 24 is likely.


Re: Ultra-low power switching boost converter - in a DIP
On 08/21/2016 12:13 PM, Peabody wrote:
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Various outfits sell SMT breakout boards fairly cheap.  I like the  
Bellin Dynamic Systems ones, available from Newark.  You might have to  
use paste and a heat gun to get it onto the breakout, but after that  
it's plain sailing.

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: Ultra-low power switching boost converter - in a DIP
On Sunday, August 21, 2016 at 6:02:31 PM UTC-4, Phil Hobbs wrote:
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+1 that was my suggestion.  
Lots on DK too.

http://www.digikey.com/product-search/en/prototyping-products/adapter-breakout-boards/2360393

George H.  

Re: Ultra-low power switching boost converter - in a DIP
George Herold says...

 > On Sunday, August 21, 2016 at 6:02:31 PM UTC-4, Phil
 > Hobbs wrote:

 >> Various outfits sell SMT breakout boards fairly cheap.
 >> I like the Bellin Dynamic Systems ones, available from
 >> Newark.  You might have to use paste and a heat gun to
 >> get it onto the breakout, but after that it's plain
 >> sailing.

 > +1 that was my suggestion.  Lots on DK too.

 > http://www.digikey.com/product-search/en/prototyping-pro
 > ducts/adapter-breako ut-boards/2360393

The problem with all those that I've found so far is that
they don't provide for the thermal/ground pad underneath the
center of the chip.  But I'm not sure I really need that.
The data sheet is pretty clear in saying that that pad
"must" be soldered to the PC board, but if I'm only looking
at a few milliamps of output current, I'm not sure that's
really necessary.

I've been watching videos on Youtube of guys using soldering
paste and heat guns to do actual reflow work.  But I still
wonder about the themal pad underneath - I guess it would
reflow there in a legit oven, but not sure about a heat gun.

Jason Betts says mount it upside down. and solder thin wires
to the pins, and a thicker wire across the thermal pad.  I'm
liking that idea more and more, subject to it broadcasting
too much noise.

Anyway, thank very much for the replies and suggestions.


Re: Ultra-low power switching boost converter - in a DIP
On Monday, August 22, 2016 at 1:47:00 PM UTC-4, Peabody wrote:
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Yeah I've done the upside down "trick" to the thermal pad with some copper tape.  
(onto copper clad.)  
I've also made a big hole in the pcb and soldered to the pad from the  
bottom. (with an iron)... hole big enough for a solder iron tip to fit through.  

George H.  
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Re: Ultra-low power switching boost converter - in a DIP
On 8/22/2016 1:28 PM, Peabody wrote:
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I don't know about this chip, but some use the thermal pad as an  
electrical connection.  I've seen one that uses it as the *only* ground  
pin.

--  

Rick C

Re: Ultra-low power switching boost converter - in a DIP
On Sun, 21 Aug 2016 18:02:23 -0400, Phil Hobbs

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Do they make QFN adapters? There's a post-it on my door that says NO
QFNS. Everybody hates them.


--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: Ultra-low power switching boost converter - in a DIP
On 8/22/2016 10:53 AM, John Larkin wrote:
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Yeah, those who aren't very good at manufacturing don't like them.  
That's why I'd never consider building my own assembly line.  Contract  
manufacturers don't seem to have any problem with them... or the big  
builders who have to save every penny they can, like in cell phones,  
etc.  QFNs are very common and very useful.

--  

Rick C

Re: Ultra-low power switching boost converter - in a DIP
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I love QFNs!  Good thermal performance, smaller than QFP and more reliable,  
and impossible to short between pins (which was interesting as I had some  
rework recently where I had to add a short between pins..).

What I don't like is the MCUs that invariably have pins coming out every  
which way. MSP430s do it. STM32s do it.  The hell is up with that?  Why  
would 32 bits of bus end up jumled!?  It literally takes as much PCB space  
to rout such a QFN, as the QFP takes up!  (The QFP would still be worse,  
though routing underneath is easier at least, not needing to allow for a  
ground pad.)

Tim

--  
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
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Re: Ultra-low power switching boost converter - in a DIP
On Tuesday, 23 August 2016 13:46:48 UTC+1, Tim Williams  wrote:

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Also, the RF emissions should be lower as there should be less
ground bounce.

John

Re: Ultra-low power switching boost converter - in a DIP
On 8/23/2016 8:46 AM, Tim Williams wrote:
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For the most part, QFNs are just QFP packages with the leads cut off.  I  
suppose there are some smaller pin count packages which have not  
corresponding QFPs and they can be uniquely small.  But a 100 pin QFN  
has the same body size as a 100 pin QFP.  I have seen QFNs with multiple  
rows of pads, but technically, I believe they become LGAs, no?


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Not sure what you mean, "every which way".  Are you talking about pads  
on all surfaces like a porcupine?  The QFN parts I have seen were still  
all planer.

--  

Rick C

Re: Ultra-low power switching boost converter - in a DIP
Den tirsdag den 23. august 2016 kl. 20.47.52 UTC+2 skrev rickman:
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I suspect he means that pins that would naturally be grouped together, like  
a data bus are spread out in a seemly  random fashion, so to route a memory  
bus you need to get to all four sides of the chip and swap the order on the way

-Lasse

Re: Ultra-low power switching boost converter - in a DIP
On 8/23/2016 3:36 PM, Lasse Langwadt Christensen wrote:
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Why would that be any different from any other package?  The order of  
pins on the package is usually the same or close to the order of pins on  
the die.

--  

Rick C

Re: Ultra-low power switching boost converter - in a DIP
Den tirsdag den 23. august 2016 kl. 21.41.04 UTC+2 skrev rickman:
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not really any different, it's just that the idea of a small package is
somewhat lost if the area you gain is just lost in routing and vias

-Lasse


Re: Ultra-low power switching boost converter - in a DIP
On 8/23/2016 4:19 PM, Lasse Langwadt Christensen wrote:
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Yes, to some extent.  But real estate can be reclaimed by using smaller  
PCB features and adding layers.  In some cases, size is more important  
that cost, so it's ok to transfer some cost to the PCB even if it ends  
up being more in total.

--  

Rick C

Re: Ultra-low power switching boost converter - in a DIP
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Right, and the lead lengths plus pad toe length, plus tolerances, takes up a  
good 4mm or so around it.

You can use that for routing instead.

I kind of suspect QFPs are easier to route anyway, as there's no pad in the  
middle (usually) that ties up all layers, grounding it.  You have very  
little room to do that under a QFN, so you end up using the pin+pad area for  
routing instead.


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As Lasse noted, I mean the pinout of GPIO ports and buses.

Even SCK, MISO and MOSI end up jumbled!  How the hell?

One plus about ATmegas is their pinouts are always nice.

Tim

--  
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
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