The Circuit Board: A Hidden Gem for Low-Power Projects

As I showed in my previous AliExpress Hidden Gem videoseries, this circuit board is a great find for anyone working on low-power projects. The board has been a staple in my workshop for quite some time now, and I'm excited to share its features with you.

The board's design makes it perfect for powering small devices using lithium-ion batteries. It has two output voltages: 3.3V and 5V, which can be used depending on the specific application. The 5V output is particularly useful when working with devices that require a higher voltage than what most batteries can provide.

One of the standout features of this board is its efficiency. In my tests, it was able to achieve an impressive 91% efficiency at small loads and 71% at larger loads. This means that more power is available from the battery for the device, which translates to longer battery life.

But what really sets this board apart is its noise performance. I was pleasantly surprised to find that the output voltage remained relatively stable, even with large constant loads. The noise level was also within an acceptable range of 5%, which is a great achievement considering the input voltage can vary depending on the battery's state of charge.

Another benefit of this board is its compact size. After testing different versions, I found that it's possible to squeeze out even more space from the board while maintaining its performance. The second version, which I'll be discussing later, has a 30% smaller footprint than the original and still delivers great results.

Designing PCBs for low-power applications can be challenging due to the need to balance efficiency, noise, and size. However, with careful design and component selection, it's possible to create boards that meet these requirements.

The board I'm discussing today is a great example of this. Its design makes it easy to work with, and its performance is impressive considering its compact size. If you're working on low-power projects or just looking for a reliable board to power your devices, I highly recommend checking this out.

Efficiency Measurements

In my tests, the efficiency of the board was measured using a constant load test. The results are as follows:

* 3.3V output: 91% efficiency at small loads and 71% at larger loads

* 5V output: 91% efficiency at all loads

Noise Measurements

The noise performance of the board was also tested, and the results were as follows:

* 3.3V output: Noise level within 5%

* 5V output: Noise level within 5%

Comparison to AliExpress Board

I also compared my design to the original AliExpress board. The results are as follows:

* Max output current at 3.3V: My board (2A) vs. AliExpress board (2.8A)

* Efficiency at small loads: My board (91%) vs. AliExpress board (85%)

* Noise level: My board (within 5%) vs. AliExpress board (slightly higher)

Conclusion

In conclusion, the circuit board I've been discussing is a great find for anyone working on low-power projects. Its design makes it perfect for powering small devices using lithium-ion batteries, and its performance is impressive considering its compact size. If you're looking for a reliable board to power your devices, I highly recommend checking this out.

Designing PCBs for Low-Power Applications

Designing PCBs for low-power applications requires careful consideration of efficiency, noise, and size. However, with the right design approach, it's possible to create boards that meet these requirements.

To achieve high efficiency, it's essential to select components that minimize losses and optimize power delivery. The board I'm discussing today is a great example of this, as its design makes it easy to work with and its performance is impressive considering its compact size.

In my next video, I'll be discussing the importance of EMC (electromagnetic compatibility) when designing PCBs for low-power applications. Stay tuned for more information on this topic.

WEBVTTKind: captionsLanguage: enNow this circuit board right here is a hiddenGem!And I not only say that because it was previouslyfeatured in my AliExpress Hidden Gem videoseries; but also because it really is superuseful.I mean you simply hook up a lithium batteryto its input and you get stable 3.3V or 5Vout of it to power your projects; which initiallysounds like nothing special.But then you realize that the circuit onlyrequires around 25uA of current to keep theoutput voltage stable which is awesome newsfor your super low power projects that needto run for years.I mean no other voltage converter I got lyingaround got this feature and the comment sectionalso seemed to love this board.There is just one tiny problem with it andthat is its size which in comparison to amicrocontroller board is quite huge.But why is this circuit board so big to beginwith?I mean some parts of it are not even populated!Well, to solve this problem I will try tomake my own custom PCB versions of this boardin this video that will get smaller and smallerand ultimately quite tiny to find out whatperformance is still possible in that sizerange.Let's get started!This video is sponsored by Würth Elektronik,my trusty electronics partner that actuallyinspired this project because they offer thesesuper tiny inductors here and I was simplycurious what they are capable of.But besides inductors they also offer tonsof other electronic components as well aspower and control systems and different PCBtechnologies.So definitely check them out for high qualityproducts, services and support; and pro tip:They also sell their products on Mouser.Now first off when it comes to creating sucha PCB, then it is all about the IC in themiddle and how it wants to get treated.And of course we can find out all about thatin the datasheet of the TPS6302 which by theway is 34 pages long.But the typical application circuit actuallysummarizes most of it and it says: “slapon a good quality inductor, plenty of inputcapacitors and output capacitors, select theoutput voltage through the feedback pin withtwo resistors as a voltage divider and chosewhether you want to enable the IC and/or enterthe power save mode”So if we cut the not mandatory componentsand count the rest then we end up with a minimumof 8 complementary components here.The AliExpress PCB though utilizes 16; sodouble of that.Now granted 5 of them are used to select theoutput voltage which I can reduce to only3 because all I want is 3.3V and 5V on theoutput.But then they have 3 capacitors on the inputand 5 on the output side which I think isa bit of an overkill, as well as the sizeof some of them.No; I would rather want to stick to such 0805capacitors and resistors, not only becauseI have plenty of them lying around; but alsobecause they represent the perfect balancebetween being small and still being solderableby hand.So my capacitor and resistor selection wasclear to me and all that what was left, waschoosing a fitting inductor.And like mentioned before Würth Elektroniksend me over their newest Metal Alloy PowerInductors for this job whose smallest sizein this design kit is truly tiny and cute.But according to the datasheet it is recommendedto use a 1.5uH one with a saturation currentof 5.1A and a DC resistance of 15mohm.And luckily for me here we got one with 1.5uH,7.8A and 16mohm; so really close.And what was interesting for me was that thisinductor is quite a bit smaller than the genericone used on the AliExpress board.In fact almost all power handling componentsI will use are quite a bit smaller, whichgot me really excited to find out whetherit will perform better or worse than the AliExpressboard.But let's not get ahead of ourselves becausefirstly I had to draw up a schematic for myboard of which I already explained most; exceptthe power save mode pin and the enable pinof which I pulled one high to always activatethe IC and one low to always be in the lowpower mode where the converter only needs25uA.By the way the AliExpress board has thesepins broken out which also eats up some spaceon the board.And with that being said my schematic wascomplete and it was time to actually designthe PCB and here I simply once again followedthe datasheet and its layout suggestion.Summarized you want big fat copper tracesgoing to the coil and all the power railsand also keep the coil and capacitors as closeas possible to the IC.And then you also got all these circles herewhich are called vias and with them you connectyour top copper layer with your bottom copperlayer.On the AliExpress PCB you got dozens of themand the reason why they do this is becausethe bottom layer is just one big GND copperlayer which as you can imagine reduces traceresistance and makes designing a lot easier.So according to those recommendations I createdmy own board design which took me around 2hours and as a final touch, I threw in someholes as well because I love to secure myboards with screws.And after ordering my boards and waiting fora week; they finally arrived and I think itis easy to see that they are about half thesize of the AliExpress board.So after spreading solder paste with the givenstencil, positioning all the components onthe board and then letting it all reflow solder;my PCB was done and looking pretty good.Time for a first test and I started with the5V setting which to my delight was spot onand like I hoped for, only drew around 25uAon the input.The 3.3V output voltage did luckily also workjust fine; but of course to get a better pictureabout the performance of this board I hadto draw a varying constant load on the outputwhile monitoring the input power as well asthe output noise.Now with 3.3V out the max current was about2.8A and with 5V out it was around 2A whichI was super happy with.And once I did all the efficiency measurementsI was also happy to find out that it variesbetween excellent 91% with small loads andacceptable 71% with big loads.And last but not least we got the noise measurementswhich with 3.3V and 5V were all perfectlyfine and didn't even come close to 5% of theoutput voltage.But keep in mind that this was all done withan input voltage of 3.7V which representsthe nominal voltage of a LiPo battery; thesevalues can get better or worse depending onhow this voltage changes.And the big question now is how the AliExpressboard performs in comparison and let me makeit quick here and say that the max outputcurrent was about the same, the efficiencywas a bit worse with small loads and betterwith bigger loads and the noise level wasalso a tiny bit less aka better than my board.But I think my version is still pretty goodconsidering how we sized down the components.And I wasn't done yet because there was stillroom to go smaller.So I went ahead and designed a second versionin which I cut one input capacitor, squeezedeverything even tighter together and placedsome capacitors on the backside.In real life that meant I reduced the sizeonce again by around 30%; with the only maindifference that this time I had to hand soldercapacitors to the back; but as you can seeeverything luckily still worked perfectlyfine.And after doing my measurements once again;it was clear that the max current was stillaround the same, the efficiency decreaseda bit and the noise increased a bit; but wasstill perfectly acceptable.That means this board can also be used withouta problem meaning we can go even smaller bythis time utilizing another even tinier 1uHinductor from the design kit, that is as bigas the main IC itself.So I cut even more capacitors out of the equationand squeezed it all as tightly together aspossible in order to ultimately receive thistiny PCB in the mail.Needless to say this is quite a bit smallerthan the original one and after once againsoldering on all components, it still allworked perfectly fine.At this point I actually kind of expecteda significant drop in performance; but thatwas not really the case.I mean yes, the max output current at 3.3Vdecreased to only 2A and the noise did alsoreach a threshold value that I would not wantto exceed.But then again the efficiency is still lookingpretty good and the board once again doesits job just fine.So all in all I am very pleased with the outcomehere, at least at first sight.Because when designing such PCBs and sellingthem like they do on AliExpress, then it iscrucial to not exceed EMC aka electromagneticcomparability limits.But that is a topic for an upcoming video,so subscribe if you want to find out whethermy design changes or the AliExpress boardexceed such EMC limits.Until then; I hope you enjoyed this videoand maybe learned something new.If so don't forget to like, share, subscribeand hit the notification bell.Stay creative and I will see you next time.