small AC-DC switch-mode supplies: are they bread-boardable?

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I'm trying to get all the kinks out of a small 250 mA 5V switch-mode supply that uses an LNK306.

 

It functions, but its hideously noisy.  I've got 0.3 V peak-to-peak of triangular-looking garbage

maybe about 2.5 kHz on the output at load.

 

All the design guides for supplies make a big deal of PCB layout considerations, so I'm wondering

if its even possible to breadboard designs of this sort, and whether breadboard effects could be

responsible for what I'm seeing.

 

I'm following this design guide:

 

     http://ac-dc.power.com/design-su...

 

with occasional reference to this design for further improvements (in particular a faster diode on the input rectifier):

 

     http://ac-dc.power.com/design-su...

Last Edited: Tue. Feb 10, 2015 - 07:10 PM
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bkerin wrote:

... I'm wonderingif its even possible to breadboard designs of this sort...

 

Depends on your breadboarding style.

 

For anything that's going to need lot of ground on the finished PCB I use 'dead bug' style prototypes over a blank copper-clad board.

 

Even though your circuit has got lethal volts floating around it's still possible. One drill, if you don;t know it, is to use a dremel to cut isolation routes through the copper to make 'tracks'.

#1 This forum helps those that help themselves

#2 All grounds are not created equal

#3 How have you proved that your chip is running at xxMHz?

#4 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand." - Heater's ex-boss

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Brian Fairchild wrote:
For anything that's going to need lot of ground on the finished PCB I use 'dead bug' style prototypes over a blank copper-clad board.
For right-side-up BusBoard is one way.

http://www.busboard.com/prototypingboards#smt

Anotther way is on Chan's, of FatFs fame, website :

ELM - Extreme Wiring on the Prototyping Board

July 14, 1997

http://elm-chan.org/docs/wire/wiring_e.html

Edit: typo, added 2nd URL.

 

"Dare to be naïve." - Buckminster Fuller

Last Edited: Tue. Feb 10, 2015 - 11:37 PM
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I breadboarded a "black regulator" from Roman Black's site: http://www.romanblack.com/smps/s... It only had 10 or 12 volts, nothing frightful. Made of junk box parts with values only in the ballpark or what he recommended, the silly thing worked. Even fairly well as I changed loads and input voltages.

 

 

 

277,232,917 -1 The largest known Mersenne Prime

Measure twice, cry, go back to the hardware store

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Not only is circuit layout critical but also the choice of components. I'd suggest that the usual plugin style breadboard is not a good choice.

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The output loop (switcher-diode-coil-caps) is the big source of noise. Any pulsed current running around a loop becomes an AM antenna, the larger the loop area or current, the worse the noise. Keep all wires be short and close together.

You may "emulate" a ground plane with twisted pair wire on all critical lines, with one wire to the common board GND.  for high impedance lines like the feedback loop, you can use shielded wire instead.
 
The output GND return works like the 'sewer' of the circuit. It carries the ripple back to the switcher IC, so the entire loop must have the lowest impedance possible, otherwise the ripple will go to the output.

Use thicker, shorter wire from diode and caps to switcher IC to reduce impedance. Caps must be of low-ESR type, and hopefully two of half the calculated value in parallel.

while(!solution) {patience--;}

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I myself gave up on that after experiencing some of what has been posted above.  Newark element14 has some nice small switching regulators that are in many cases drop in replacements for the 78xx series linear regulators.  THey have others that are also on ready made pc boards that you can solder lead wires to and then snap into breadboards and the like.

 

Jim

If you want a career with a known path - become an undertaker. Dead people don't sue! - Kartman

Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?  - Lee "theusch"

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB user

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jgmdesign wrote:
THey have others that are also on ready made pc boards that you can solder lead wires to and then snap into breadboards and the like.
The following caught my attention from, IIRC, the most recent Digi-Key mailing (United States Postal Service that is wink

PBK-3-3-B CUI Inc | PBK-3-3-B-ND DigiKey Electronics

Digi-Key

Product Index > Power Supplies - Board Mount > AC DC Converters > CUI Inc PBK-3-3-B

http://www.digikey.com/product-detail/en/PBK-3-3-B/PBK-3-3-B-ND/4918691

Though that model is not in-stock maybe a similar model by that make is in-stock.

Edit: copy image.

"Dare to be naïve." - Buckminster Fuller

Last Edited: Sun. Feb 15, 2015 - 01:09 AM
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That *is* attention-getting. Seems pricey, but then again it is a one-stop-shopping solution ;)

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

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"Fast.  Cheap.  Good.  Pick two."

"Read a lot.  Write a lot."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

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bkerin wrote:
All the design guides for supplies make a big deal of PCB layout considerations

That's because what happens during the switching transients is very important to a switch-mode power supply!

 

It's in those transients that "parasitic" and "stray" L, C, and R become significant and have to be managed well.

 

Solderless breadboards are not good for that!

 

Quote:
breadboard effects could be responsible for what I'm seeing.

I think that must be at least a possibility.

 

Most of the big SMPS chip purveyors these days have pretty detailed free simulation tools - take a look at the peak currents that these show within the circuit, and think what effects the typical solderless breadboard contact resistance would have there...

 

 

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while(!solution) {patience--;}

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It's worth noting that the OP isn't talking about DC-DC converters or regulators. He's developing an AC mains to DC non-isolated converter.

 

Any breadboard or technique will need to work with those sorts of voltages.

#1 This forum helps those that help themselves

#2 All grounds are not created equal

#3 How have you proved that your chip is running at xxMHz?

#4 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand." - Heater's ex-boss

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G0NZ4L0 wrote:
I've used all these SMPS on breadboards:

But just using them is an entirely different matter from trying to breadboard the internals of a SMPS - isn't it?!

Top Tips:

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  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
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Competitors to Power Integrations (PI) are Monolithic Power Systems (MPS) and ON Semiconductor; many others but I don't recall the marks.

PI LinkSwitch-TN, MPS EasyPower (was).

An MPS evaluation board is one layer, SMT parts on the bottom, thru-hole parts on top.

Simple PCB; might mount it on or near the breadboard.

Ref.

Monolithic Power Systems

MP156

Offline Primary Side 3W Regulator, 30mW No-Load Power

http://www.monolithicpower.com/Products/Product-Detail?ProductID=6

Evaluation Board

http://www.monolithicpower.com/DesktopModules/DocumentManage/API/Document/GetDocument?id=10 (PDF, EV156..., 2.2MB)

(go to page 8 for "Figure 3 — Bottom Layer")

http://www.mouser.com/Search/Refine.aspx?Keyword=EasyPower

 


ON Semiconductor

NCP107X, 12 Vout, Off-line Buck Regulator

Design Note – DN05058/D

http://www.onsemi.com/pub/Collateral/DN05058-D.PDF (161KB)

...

Output Voltage  5 to 36 Vdc depending on selected Z1 zener value
Output Ripple  Less than 1%
Typical Current 100 to 350 mA
Max Current    150 mA with NCP1071, 400 mA with NCP1077 (see matrix below)
Min Current   zero

...

... where isolation from the AC mains is not required.

Gerber ZIP file exists but did not view it.

http://www.onsemi.com/PowerSolutions/evalBoard.do?id=NCP1071SOTGEVB

 

Edit: added ON, URL for ON EVB.

"Dare to be naïve." - Buckminster Fuller

Last Edited: Tue. Feb 17, 2015 - 05:52 PM
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What is LNK306? What kind of a component is this? Where it has the applications? How it is generating noise in your circuit? As you are saying about the design problem of PCB then i am agree with the others that the bad PCB designing causes the noise in the circuits. So you must go for the good PCB design and manufacturing.

 

Leiterplattenbestückung

Last Edited: Fri. Sep 11, 2015 - 04:21 PM
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I have built small appliance controllers with the LNK for the power supply, it is NOT something I would suggest for a beginner to use, as it is meant to be used in NON-isolated AC / DC supplies, these are very dangerous for someone who does not know what they are doing or provides the proper shielding and protection.   These do not lend themselves to breadboarding!  

Stick to using common isolated AD/DC supplies for your breadboard circuits.

 

Jim

 

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For breadboarding switch mode power supplies, I start with the provided "suggested layout" and a piece of unetched (copper clad) circuit board material. I take a good, stout knife and simply cut away not needed copper. Then, holes are drilled where necessary, and parts are soldered.

 

Yes, as far as noise is concerned, layout IS important. But, several other things are, also. These include having correct capacitors (with sufficiently low ESR and proper value), correct inductors (low enough series resistance and high enough saturation current and proper value), and correct diodes (fast enough turn-off, sufficient reverse breakdown voltage, and high enough current rating combined with low enough forward voltage at that current).

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net