How TINY Can I go? The BEST Power Board is here!

Now this circuit board right here is a hidden Gem! And I not only say that because it was previously featured in my AliExpress Hidden Gem video series; but also because it really is super useful. I mean you simply hook up a lithium battery to its input and you get stable 3.3V or 5V out of it to power your projects; which initially sounds like nothing special. But then you realize that the circuit only requires around 25uA of current to keep the output voltage stable which is awesome news for your super low power projects that need to run for years. I mean no other voltage converter I got lying around got this feature and the comment section also seemed to love this board. There is just one tiny problem with it and that is its size which in comparison to a microcontroller board is quite huge. But why is this circuit board so big to begin with? I mean some parts of it are not even populated! Well, to solve this problem I will try to make my own custom PCB versions of this board in this video that will get smaller and smaller and ultimately quite tiny to find out what performance is still possible in that size range. Let's get started! This video is sponsored by Würth Elektronik, my trusty electronics partner that actually inspired this project because they offer these super tiny inductors here and I was simply curious what they are capable of. But besides inductors they also offer tons of other electronic components as well as power and control systems and different PCB technologies. So definitely check them out for high quality products, services and support; and pro tip: They also sell their products on Mouser. Now first off when it comes to creating such a PCB, then it is all about the IC in the middle and how it wants to get treated. And of course we can find out all about that in the datasheet of the TPS6302 which by the way is 34 pages long. But the typical application circuit actually summarizes most of it and it says: “slap on a good quality inductor, plenty of input capacitors and output capacitors, select the output voltage through the feedback pin with two resistors as a voltage divider and chose whether you want to enable the IC and/or enter the power save mode” So if we cut the not mandatory components and count the rest then we end up with a minimum of 8 complementary components here. The AliExpress PCB though utilizes 16; so double of that. Now granted 5 of them are used to select the output voltage which I can reduce to only 3 because all I want is 3.3V and 5V on the output. But then they have 3 capacitors on the input and 5 on the output side which I think is a bit of an overkill, as well as the size of some of them. No; I would rather want to stick to such 0805 capacitors and resistors, not only because I have plenty of them lying around; but also because they represent the perfect balance between being small and still being solderable by hand. So my capacitor and resistor selection was clear to me and all that what was left, was choosing a fitting inductor. And like mentioned before Würth Elektronik send me over their newest Metal Alloy Power Inductors for this job whose smallest size in this design kit is truly tiny and cute. But according to the datasheet it is recommended to use a 1.5uH one with a saturation current of 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 this inductor is quite a bit smaller than the generic one used on the AliExpress board. In fact almost all power handling components I will use are quite a bit smaller, which got me really excited to find out whether it will perform better or worse than the AliExpress board. But let's not get ahead of ourselves because firstly I had to draw up a schematic for my board of which I already explained most; except the power save mode pin and the enable pin of which I pulled one high to always activate the IC and one low to always be in the low power mode where the converter only needs 25uA. By the way the AliExpress board has these pins broken out which also eats up some space on the board. And with that being said my schematic was complete and it was time to actually design the PCB and here I simply once again followed the datasheet and its layout suggestion. Summarized you want big fat copper traces going to the coil and all the power rails and also keep the coil and capacitors as close as possible to the IC. And then you also got all these circles here which are called vias and with them you connect your top copper layer with your bottom copper layer. On the AliExpress PCB you got dozens of them and the reason why they do this is because the bottom layer is just one big GND copper layer which as you can imagine reduces trace resistance and makes designing a lot easier. So according to those recommendations I created my own board design which took me around 2 hours and as a final touch, I threw in some holes as well because I love to secure my boards with screws. And after ordering my boards and waiting for a week; they finally arrived and I think it is easy to see that they are about half the size of the AliExpress board. So after spreading solder paste with the given stencil, positioning all the components on the 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 the 5V setting which to my delight was spot on and like I hoped for, only drew around 25uA on the input. The 3.3V output voltage did luckily also work just fine; but of course to get a better picture about the performance of this board I had to draw a varying constant load on the output while monitoring the input power as well as the output noise. Now with 3.3V out the max current was about 2.8A and with 5V out it was around 2A which I was super happy with. And once I did all the efficiency measurements I was also happy to find out that it varies between excellent 91% with small loads and acceptable 71% with big loads. And last but not least we got the noise measurements which with 3.3V and 5V were all perfectly fine and didn't even come close to 5% of the output voltage. But keep in mind that this was all done with an input voltage of 3.7V which represents the nominal voltage of a LiPo battery; these values can get better or worse depending on how this voltage changes. And the big question now is how the AliExpress board performs in comparison and let me make it quick here and say that the max output current was about the same, the efficiency was a bit worse with small loads and better with bigger loads and the noise level was also a tiny bit less aka better than my board. But I think my version is still pretty good considering how we sized down the components. And I wasn't done yet because there was still room to go smaller. So I went ahead and designed a second version in which I cut one input capacitor, squeezed everything even tighter together and placed some capacitors on the backside. In real life that meant I reduced the size once again by around 30%; with the only main difference that this time I had to hand solder capacitors to the back; but as you can see everything luckily still worked perfectly fine. And after doing my measurements once again; it was clear that the max current was still around the same, the efficiency decreased a bit and the noise increased a bit; but was still perfectly acceptable. That means this board can also be used without a problem meaning we can go even smaller by this time utilizing another even tinier 1uH inductor from the design kit, that is as big as the main IC itself. So I cut even more capacitors out of the equation and squeezed it all as tightly together as possible in order to ultimately receive this tiny PCB in the mail. Needless to say this is quite a bit smaller than the original one and after once again soldering on all components, it still all worked perfectly fine. At this point I actually kind of expected a significant drop in performance; but that was not really the case. I mean yes, the max output current at 3.3V decreased to only 2A and the noise did also reach a threshold value that I would not want to exceed. But then again the efficiency is still looking pretty good and the board once again does its job just fine. So all in all I am very pleased with the outcome here, at least at first sight. Because when designing such PCBs and selling them like they do on AliExpress, then it is crucial to not exceed EMC aka electromagnetic comparability limits. But that is a topic for an upcoming video, so subscribe if you want to find out whether my design changes or the AliExpress board exceed such EMC limits. Until then; I hope you enjoyed this video and maybe learned something new. If so don't forget to like, share, subscribe and hit the notification bell. Stay creative and I will see you next time.

Channel: GreatScott!

Views: 272,329

Keywords: aliexpress, board, remake, smaller, design, pcb, printed, circuit, make, voltage, converter, buck, boost, tps, 6302, tutorial, guide, beginner, beginners, greatscott, greatscott!, electronics, electronic, mini, tiny, project, current, battery, low, power, super, sleep, microcontroller, arduino, esp, deep, mode, save, enable, inductor, coil, capacitor, resistor, smd, surface, mount, device, efficiency, noise, measure, measuremet, compare, comparison, homemade, solder, how, to, maximum, output, input

Id: XAcW4c5qIMc

Length: 11min 54sec (714 seconds)

Published: Sun Jan 28 2024