USB Hub Design - Part 1/x - Overview and Theory

[@julesinspaaace]

My vote is for unified power + 3.1 data, that's a lot more interesting 😊

[@leonardmilcin7798]

Great topic! I am currently learning electronics design (after working in development for over 20 years) and videos showing more of design process and decision making are extremely helpful:)

[@Fazzwrld]

Alternative idea: Stay at lower speeds but design the system with a >7.5kV isolation between upstream and downstream. That would be great for keeping your computer's USB ports from frying when doing high(er) voltage experiments. Isolated 4 port hubs are also really rare, so there is a niche market opportunity. I'd pay $300 for a well designed isolated hub with external power. Single 5kV USB isolators are between $120 - $200. High voltage isolation also provides for interesting PCB design choices. Well, I just had to replace my laptop's system board due to a happy discharge accident into the USB connected micro controller. So I might be biased :)

[@sanityd1]

Why 7.5kV? $300usd wouldn't be enough

[@Fazzwrld]

​@@sanityd1 7.5kV seems to be the soft spot where you can still buy off the shelf stuff. For example, for low isolation requirements up to 3kV the LTM2884 is a good option with simple design requirements, and it includes 500mA current delivery. For 7.5kV Analog Devices has the LTM2894, but current delivery is done via external isolation transformers. This makes the design more complex, but also more interesting for the sake of this channel. If you go 10kV or higher, it might be difficult to find demo boards, schematics and all that so it is way more difficult to develop a solution in a couple of KZbin videos. You might have to use high speed optical isolators like the OPI1268s which can do up to 2MBit TTL. But I don't know enough about USB to make an educated guess. Regarding the price: That depends a lot on your target market segmentation, expected sales volume, sales channels etc. My intent was to show that there is an interesting and underserved market segment for USB hubs outside the $20 PC peripherals stuff on Amazon.

[@MicroTypeEngineering]

Woah. Never really knew this was a need. Seems like it's a super popular idea! Can you share some examples of use cases where this would be useful? Definitely will look into it for a future project!

[@Fazzwrld]

​@@MicroTypeEngineering Our use case: We develop small form factor time of flight sensors. The drift tube has a linear 10-20kV electrostatic field gradient to separate ionized compounds by their ion mobility. Ion packets are inserted into the drift tube using an ion shutter (google Bradbury Nielsen gate or better Tri State ion shutter). This gate sits at the high potential and is switched by 3 signal lines coming from an off-PCB uC. On the PCB, all the switching MOSFETS etc. are floated up to the high potential. So you have 75-300V gate pulses riding on top of 10kV. During prototyping we use an Analog Discovery 2 for data capture, which sits behind a 10E10 current to voltage amplifier. Now, if something happens, you can kiss the AD2 good bye, potentially the uC and potentially the amplifier as well, and your lab PC's USB. It's a half days work to put everything back together, so there is value in avoiding burning through USB oscilloscopes. Especially with the AD2 getting more and more expensive. Other applications can be x-ray device development or ionizers like dielectric barrier discharge or a corona discharge. Would really appreciate some videos on that!

[@MicroTypeEngineering]

@Fazzle if you haven't already, join the discord! discord.gg/Z4P5yScC

[@ahaququq]

I just make theoretical designs for fun (copy the reference schematic) in KiCad. Now i want to make them possible to work IRL. Great series!

[@ahaququq]

Currently i'm looking at the documentation of "TUSB8041 Four-Port USB 3.0 Hub". It was the only one in KiCad with usb 3.x Edit: Writing comments while still watching the video be like :D

[@samk2630]

This is my next project, excited to learn so much from your informative videos.

[@missamo80]

My vote: go for as high a speed as you can (3.1), and do external power. It's gonna be a long project either way so might as well make it interesting on the USB side by showing the work to do super speed. External power would be a neat addition too.

[@toastrecon]

How do I explain to my 10 year old self that my "Saturday Morning Cartoons" are USB hub design? Ha. That said, 10 year old me was making PCBs out of copper clad boards, stickers, and a little plastic box with acid etchant. Looking forward to this series. I was just thinking the other day about how one would design a USB hub/device.

[@MicroTypeEngineering]

Haha! Awesome

[@suncrafterspielt9479]

love these videos... happy for the series :D

[@suncrafterspielt9479]

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[@thekaduu]

TI is the best!

[@RazzaDazza0]

Hi this is really informative and thank you so much for making this video but I would suggest that you change the thumbnail because it shows a usb-a connector so I almost didn't click on this video because I thought it wouldnt be covering usbc I only clicked on it because I was curious about what your channel might be about. I think the thumbnail and title might be why this doesn't have more views than it absolutely deserves. I suggest editing the thumbnail to instead include a usbc connector right next to your head and for the title I suggest you put "Designing a USB-C Hub From Scratch Part 1" or something like that. Or you can retitle it to instead focus more on the specifications so something like "The design behind usbc and how to use it" or something.

[@flavioamieiro]

I also vote for 3.1 speed first and, if possible, self-powered. But I would go for external power and 3.1 speed if both are too much.

[@Theubershadow]

Maybe to make it even more interessting, you can include an external power input (maybe type C too?), which can also be used to charge your upstream device or so that you can use one of the type A ports for charging a phone.

[@Amsoliemani]

Good

[@silentbob19861]

Yes yes yes. USB 3.1 hub would be great topic... I've failed multiple times with it....

[@justinraine]

How would the architecture need to be adapted to add a USB-C passthrough port? The mux supports DRP but I assume it's more complicated than adding another HD3SS2520 after the hub, connected to a USB-C port?

[@rick_er2481]

Great videos! keep it up :)

[@Amsoliemani]

😍

[@keithmar5996]

External power and high speed. And ti needs to sponsor you!

[@kamleshchavan7451]

Hello sir how r u, nice knowledgeable video, I'm from India, sir do have any video explaining how to design a 433 MHz transmitter and receiver module circuit , which is used usually in RC control toys etc, hope this will not obligate you, thank you

[@michaelcutler7481]

+1 vote for 3.0/3.1 speed and self-powered (if possible) with external power as a backup option.

[@sriramchava8062]

Can you please make one for usb A downstream and ethernet upstream

[@sanityd1]

External 12Vin and internal power (user decides, auto detect), USB 3.2 on one port and USB HS on the other 3.

[@robertharker]

I am building a neopixel led light wand which need 3a of power. Can a type A connector use passive power delivery signaling? My reading tells me that a UFP can request up to 3a with CC logic pullup resistors. But a type A connector does not have any CC pins. How does an inexpensive 3a type A USB power supply deliver 3a? Does it simply give any USB device 3a? Or is there some other mechanism? Any pointers would be useful.

[@MicroTypeEngineering]

Yeah, only type c has the cc pins. Plenty of products violate USB protocol