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

Summary

The video covers customizing and minimizing the size of a 3.3/5V DC voltage regulator circuit board from AliExpress while maintaining performance. It starts by analyzing the original commercial board's design and components. Then, smaller versions are iteratively created using smaller 0805 components and tiny power inductors from Würth Elektronik. Despite significantly reducing the boards' size, the new versions perform well in terms of efficiency, noise, and output current. Their EMC compatibility will be evaluated in a future video. Overall, it shows that with careful design, substantial miniaturization of this regulator board is possible while retaining adequate functionality.

Takeaways

• 😀 The video features a useful but large DC-DC converter circuit board from AliExpress and tries to create more compact custom versions
• 👨‍🔬 The key component is the TPS6302 IC which needs proper selection of inductors, capacitors and resistors to work well
• 🔬 Several iterations of new board designs are created, testing different component sizes and placements for maximum miniaturization
• 👍 The custom boards perform very well, with only minor performance tradeoffs compared to larger versions
• 🔋 Efficiency, output current capability and noise levels are characterized across different designs and load conditions
• 😮 The smallest 1cm x 1cm design works surprisingly well, although efficiency decreases and noise increases slightly
• 📏 Component sizes play a major role in board miniaturization, with tiny 0805 passives and compact power inductors being key
• 💡 Good PCB layout following datasheet guidelines is also critical for achieving excellent performance
• ⏩ Further testing is needed to ensure the boards meet EMC requirements before production and sales
• 👋 The project demonstrates the potential for significant size reductions of useful circuit boards through careful optimization

Q & A

What makes the circuit board featured in the video a 'hidden gem'?

The circuit board is a hidden gem because it can provide stable 3.3V or 5V output while only requiring around 25uA of current to keep the output voltage stable. This makes it great for super low power projects.

Why is the AliExpress circuit board so large?

The AliExpress circuit board is large because it utilizes more components than necessary, including extra capacitors and resistors. It also breaks out the power save and enable pins which takes up space.

How did the author reduce the size of the circuit board?

The author reduced the size by only using the minimum necessary components, switching to smaller 0805 sized capacitors and resistors, and utilizing tiny 1.5uH inductors from Würth Elektronik.

How did the author's smaller boards compare in performance?

The author's smaller boards had slightly decreased max current, efficiency, and increased noise compared to the original AliExpress board, but overall still performed very well.

What is the purpose of the vias on the circuit board?

The vias connect the top and bottom copper layers, allowing the use of a solid bottom GND plane to reduce resistance.

What measurements were done to evaluate board performance?

Measurements included max output current, efficiency across different loads, and noise levels to quantify performance.

What was the smallest board size achieved?

The smallest board achieved was around 30% smaller than the original AliExpress board.

What IC is at the heart of the converter circuit?

The key IC in the converter circuit is the TPS6302.

What is the purpose of the feedback pin on the IC?

The feedback pin allows selection of the output voltage through a resistor voltage divider.

What future test is planned for the boards?

The author plans to test if the boards exceed any electromagnetic compatibility (EMC) limits.

Outlines

00:00

😀Introducing the Tiny Power Converter Board

The first paragraph introduces a tiny power converter circuit board from AliExpress that efficiently provides stable 3.3V or 5V output from a lithium battery. It highlights the board's usefulness for low power projects despite its large size. The speaker plans to create custom PCB versions to shrink its size while preserving performance.

05:03

😊Designing the First Smaller Custom PCB Version

The second paragraph covers the process of designing a smaller custom PCB version of the power converter board. The speaker chooses components based on the IC datasheet, focusing on small 0805 capacitors and resistors. A tiny inductor from Würth Elektronik is used. The resulting PCB is half the size but performs similarly to the original.

10:03

😎Creating an Even Smaller Second PCB Version

The third paragraph discusses creating an even smaller second PCB version, reducing size by 30% by squeezing components together tighter. Some capacitors are hand soldered to the backside. Performance decreases slightly but is still acceptable. There is room to go even smaller.

Keywords

💡PCB

PCB stands for 'Printed Circuit Board'. It is used to build electronic circuits by mounting components like integrated circuits, resistors, capacitors etc. on a non-conductive board. The transcript mentions designing multiple custom PCB versions of the voltage converter circuit board to make it smaller in size.

💡Voltage Converter

A voltage converter is an electronic circuit that converts one DC voltage level to another DC voltage level. The main IC TPS6302 in the video is a voltage converter that provides stable 3.3V or 5V output from a lithium battery input.

💡Inductor

An inductor is a passive electronic component that stores energy in its magnetic field. Inductors are a key component in voltage converter circuits. The video compares different sizes of inductors from Würth Elektronik to see the impact on the circuit's power and efficiency.

💡Efficiency

Efficiency refers to the ratio between the output power delivered versus the input power consumed in an electronic circuit. The higher the efficiency, the less power is wasted. The video measures and compares the efficiency across different custom PCB designs.

💡Low Power

Low power refers to electronic devices and circuits that consume very little electrical power. The voltage converter IC uses only 25uA in standby power saving mode, making it suitable for low power projects needing years of battery runtime.

💡Noise

In electronics, noise refers to unwanted fluctuations or interference in the voltage or current signals. Lower noise levels in a power supply circuit are desirable. The video examines output voltage noise across the different sized PCB designs.

💡SMT Components

SMT stands for Surface Mount Technology. SMT components like 0805 resistors & capacitors are smaller than through-hole components and allow for more compact PCB designs, as used in the video.

💡Hand Soldering

Hand soldering refers to the manual process of melting and applying solder to attach electronic components to a PCB. The video demonstrates hand soldering capacitors onto the smaller custom PCB versions.

💡EMC

EMC refers to Electromagnetic Compatibility which means the ability of electronic devices/systems to function properly in its electromagnetic environment. The video hints at examining the custom PCB design's EMC performance.

💡AliExpress Board

This refers to the large voltage converter PCB board from AliExpress that the video analyses and then attempts to shrink down in size while retaining most of its functionality.

Highlights

The circuit board is useful for low power projects due to its low quiescent current.

The board is large compared to a microcontroller board.

Many components on the board seem unnecessary.

The goal is to make smaller custom PCB versions with similar performance.

The minimum component count is 8 based on the datasheet.

Small 0805 components are used for size and solderability.

A tiny 1.5uH inductor is used despite being smaller than the original.

The custom boards are about half the size of the original.

The smaller board has similar max output, efficiency, and noise performance.

Further size reduction impacts performance but is still functional.

EMC testing is needed before selling the boards.

The sponsor provides high quality electronic components.

Following the datasheet layout guidelines is key.

Vias connect the top and bottom copper layers.

Hand soldering capacitors on both sides enables further size reduction.

Transcripts

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.