I'd love a little grilling tell me EVERYTHNG i did wrong please - Page 1
Forum section: electronics / beginners

author: Yunadex
author_rank: Contributor
timestamp: June 01, 2025, 04:56:22 pm
content: trying to make a PCB for the first time please tell me everything i did wrongbasically trying to make a basic charger ( power brick bought over the counter ) with 10 male USB-C ports for a bunch of small devices as a dockno idea if i did anything correctly, thicc boi trace length is 3mm and smaller ones are mostly 0.2-0.3mm

author: Yunadex
author_rank: Contributor
timestamp: June 01, 2025, 05:04:49 pm
content: heres the schematic as a screenshot too

author: MariuszD
author_rank: Regular Contributor
timestamp: June 01, 2025, 05:56:40 pm
content: C1 C2 U13 in series, this is wrong.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 01, 2025, 06:20:56 pm
content: When drawing a schematic it is common practice to have the positive rail on the top and the ground on the bottom.Quote from: Simmed on June 01, 2025, 05:18:08 pmIt is not going to survive such a current anyway with those small traces to the connectors, but this is only when the connected devices are actually going to take the full amount.The two parallel MBR16200 diodes in series with the supply are an indication that the OP is aware of the possibility of high currents. Correctly spotted by MariuszD is that this thing is not going to work due to the over voltage protection and the smoothing caps being in series with the supply voltage.These components need to be connected between the positive rail and the ground rail.The circuit board is no good with these very small traces bringing the supply to the connectors. The board is only using a very small part of the bottom layer for some copper, which is a waste of good copper space. To support 3A to the connector it is best to make use of vias and a lot of copper on the bottom plane to connect the connector pins to that, as close as possible to the connector.

author: Yunadex
author_rank: Contributor
timestamp: June 01, 2025, 07:34:50 pm
content: Thank you for pointing these things out! I guess i used the wrong resistors as i was trying to design it to only pull 10A total 1A per port since my devices will only have 160mAh batteries anywayI'll try correct the rest too

author: Simmed
author_rank: Frequent Contributor
timestamp: June 01, 2025, 08:58:42 pm
content: here is another questiondo you think you need per channel fuse/PTC ? ~~ 0.7A ?which also means CC Rp is not 5.1kyou probably only need 0.5A per channel?which means everything can be thrown awaybecause the diode can now be SMD 1A per channel (5cents), U12 is $2there are USB-C which are charge port only, power +CC pin (called a 6pin type i think)i have not started to talk about C1 C2but i think i will stop here

author: golden_labels
author_rank: Super Contributor
timestamp: June 02, 2025, 03:34:24 am
content: Shield connectors on your USB sockets are floating. All shield pins should be connected to GND for both electrical and mechanical reasons. In your case the latter is more important.If you moved the pull-down resistors to the sides of receptacles, you could route thick GND connectors right to the sockets, including between them. You can also mirror connections on each other socket. This way you can have a thicker GND and VCC line to each pair, instead of separate, thin ones.You’re also not making use of the two layers you have at your disposition. Don’t limit yourself to long, narrow traces, if you can just flood this with copper.The invalid capacitor connection has already been noted, but there is one more issue. It’s certainly cheaper this way, but if we’re to be perfectionists: you have large PCB area wasted by having to put that huge capacitor. Using multiple smaller ones just by the connectors will use less space, while offering the same (or larger) total capacitance and adding some separation between connected devices. But your current design, with one big capacitor, isn’t an error either.

author: EEVblog
author_rank: Unknown
timestamp: June 02, 2025, 04:05:24 am
content: Unfortunately there are many issues here as people have pointed out.It will take a careful step-by-step to sort them out.

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 05:53:19 am
content: Thank you for all the info!It is my first ever try doing something like this so i honestly am pretty happy with the amount of mistakes i get that it wouldn't work but i thought it'd be much worse!

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 06:49:04 am
content: the only thing i cannot seem to get is vertical male usb c plugs of the 6pin variety so im gonna have to go with the 24pin ones but otherwise i should be able to implement it all

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 06:54:21 am
content: nvm found one

author: golden_labels
author_rank: Super Contributor
timestamp: June 02, 2025, 07:00:02 am
content: One more note. Are you going to order the entire assembled board, or only the PCB and then solder components yourself?If you want to solder it yourself, the layout must take into account your ability to access pads. A tightly packed row of USB vertical connectors is hard to solder by hand, if possible at all.They may also contain plastic elements, which are particularly vulnerable to overheating.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 02, 2025, 07:11:08 am
content: Quote from: golden_labels on June 02, 2025, 07:00:02 amVery good point. You might also want to get the components first before ordering the PCB. Print out your design and see if the components fit on the pads and that it allows you to access the parts to solder them.It goes without saying that you always start with the smallest parts first, because otherwise it might be very difficult to solder them.

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 07:39:23 am
content: i made this now,i was planning to just order an assembled board for ease i highly doubt i'd be able to solder little teeny usb C port pads myself with my pinecil xD

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 02, 2025, 08:47:46 am
content: Why the diode in series with the current limiter? There is no need for it unless you need to drop some voltage. Same for the fuse. You are using a current limiter IC to not go over the set current, so the fuse should never trip.Also you need to add a decoupling capacitor on the input of the TPS2552 and the EP pin has to be connected to ground.

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 09:06:08 am
content: the diode is for reverse current and reverse polarity protection? at least that's what i've read

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 09:10:21 am
content: Quote from: pcprogrammer on June 02, 2025, 08:47:46 amis this correct ish then?

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 02, 2025, 09:28:50 am
content: Did you even read the datasheet of the TPS2552?https://www.ti.com/lit/ds/symlink/tps2552.pdfRight there on the first page is a sample schematic of a typical setup.Capacitors in series with a supply line will never work. A capacitor blocks DC (direct current) and only lets through AC (alternating current). This is why they are connected between the supply voltage and ground. This way they suppress noise and oscillations on the supply line.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 02, 2025, 09:32:44 am
content: Quote from: Yunadex on June 02, 2025, 09:06:08 amYes, but that is only needed when you expect a voltage to be presented on the USB-C connector. The problem with such a diode is that it drops up to a volt depending on the current. For charging a battery it might not be a big problem, but it is always good to think about the why or why not.Edit: The TPS2552 also provides this functionality. Stated on the first page of the datasheet.Quote

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 09:37:59 am
content: Quote from: pcprogrammer on June 02, 2025, 09:28:50 amyeah as i said my first time making a PCB so trying to make sense of all i need to look at xD ok so i put a capacitor like that but from the 5V to ground then?

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 09:39:45 am
content: like so?

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 02, 2025, 09:44:25 am
content: Quote from: Yunadex on June 02, 2025, 09:39:45 amYes. Now switch to the proper ground symbol when drawing schematics. The one you are using is the symbol for protective earth. Not a real issue, but more common practice. Also keep them pointing down. Makes reading schematics easier.

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 09:45:59 am
content: okay will keep that in mind thank you very much!also mail me some Saucijenbroodjes please i miss them

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 02, 2025, 09:47:48 am
content: Quote from: Yunadex on June 02, 2025, 09:45:59 amCan't get those here in France. That is where I live, even though I'm Dutch.

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 09:53:54 am
content: so you suffer like me XDI'm half Dutch half Finnish live in Finland

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 10:06:05 am
content: so this is about correct now for the schematic right?Then for wiring i was going to do 1.5-2mm traces for 2oz copper for the main 5A traces and for each port branch something like 1.5mm?

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 02, 2025, 10:46:15 am
content: Yes that looks better. One thing, the TPS2552 datasheet mentions 120uF capacitors before the USB connectors, instead of 1uF.Changing it to that would improve on single outlet stability and you can reduce the capacitors at the power supply input connector to smaller ones.Look for SMD based aluminum electrolytes. 10V types like these for instance:https://www.lcsc.com/product-detail/Aluminum-Electrolytic-Capacitors-SMD_PANASONIC-EEEFK1A121SR_C336771.htmlFor the PCB use the bottom layer to distribute the ground and if possible also the supply, or use a copper poor on the top to create the supply chain. Make use of vias to connect the pads on the top to the bottom, but don't put the vias in the pads.Best to show us the result before ordering.

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 11:20:37 am
content: okay this is the schematic with everything implemented i think?and yeah i will definitely show it before ordering, i am more learning right now anyway and was going to make this good enough to order in the future as i am still finalizing my designs for the devices im plugging into this ( just case etc wise )

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 02, 2025, 11:30:01 am
content: Looks ok.

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 12:17:10 pm
content: okay 1 port is fully wired did i do anything wrong here?

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 12:58:31 pm
content: had the safety pins not connected and was missing one ground connection think it's now correct

author: mtwieg
author_rank: Frequent Contributor
timestamp: June 02, 2025, 12:59:50 pm
content: Have you actually verified that this circuit (specifically the CC/VCONN terminations and this connector, with no cable in between) together with whatever device you're charging will actually provide the current you desire? If not, I would do that before finalizing this design. USB-C is full of caveats, don't want to be surprised later on...

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 01:06:16 pm
content: Quote from: mtwieg on June 02, 2025, 12:59:50 pmthink so? im limiting the current to 0.5A ( for ease of lower power circuit and i don't need much for the device i will mainly be plugging in ) and im using a ripoff Nice!Nano NRF52840 development board which should then only draw what it needs as far as i am aware

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 02:58:50 pm
content: ok so this is what my schematic + how it's wired so far looks likeagain im trying to basically make a 10 port usb charger but wil Male plugs instead of female is this somewhat correct im starting to slowly get more confused, do i need any charge negotiations or what my brain is slowly getting fried atm

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 02, 2025, 04:42:49 pm
content: Quote from: Yunadex on June 02, 2025, 12:58:31 pmSince you are using EasyEDA it is possible to export the project and post it here. I will modify things a bit to show you the way to do it, because this trace setup will still be problematic with larger currents.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 02, 2025, 04:46:18 pm
content: Quote from: Yunadex on June 02, 2025, 01:06:16 pmYou mean with the new CC resistor setup?Because your current limiting with the TPS2552 is set to over 1A.

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 04:49:14 pm
content: i changed the schematic to be like this now for better USB spec compliance and such,here is the EasyEDA file in zip but the PCB is the old schematic atm still on it

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 02, 2025, 05:12:39 pm
content: I reworked the schematic back to the old one with only one port to show how a schematic becomes more readable.Not sure if the new setup with that extra IC is needed, but I'm not up to speed with USB-C specifications.Will provide a PCB layout later.

author: Yunadex
author_rank: Contributor
timestamp: June 02, 2025, 05:25:08 pm
content: Ohh yeah that does look way more readable, I'll try to match that tomorrow evening with the extra IC as that'd bring it all up to spec i think,This is mostly for a personal project but if all goes well i was planning to maybe become a seller for SmolSlimes and if i can successfully make a nice charging dock that'd be great

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 02, 2025, 05:59:25 pm
content: Here are the project files for both the schematic and the PCB.This gives you an idea of how things can be done.Due to crappy component footprint design there are DRC errors, so you might want to look into that. The one on the power connector can be avoided by using a copper area instead of a solid region.

author: Yunadex
author_rank: Contributor
timestamp: June 03, 2025, 01:40:14 pm
content: a lot cleaner now i think! next is to follow your example on the PCB :3

author: Yunadex
author_rank: Contributor
timestamp: June 03, 2025, 02:50:10 pm
content: how it's looking now :3think it's not bad right?

author: Yunadex
author_rank: Contributor
timestamp: June 03, 2025, 03:07:27 pm
content: okay included the PCB file now to get a final ish? check, there is some DRC errors idk if i need to be concerned about them?otherwise i think it's wired, though a little rough i think it should work right?

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 03, 2025, 03:27:39 pm
content: Quote from: Yunadex on June 03, 2025, 01:40:14 pmTry not to squeeze to much in on small bits to avoid component labels crossing the wires. It can be drawn cleaner when you rotate the IC above the USB connector.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 03, 2025, 03:30:51 pm
content: Quote from: Yunadex on June 03, 2025, 02:50:10 pmYou are still using thin traces for the supply on to the USB connector. It can be done with a copper area.Edit:Your 120uF capacitor is connected the wrong way round.The center pad of the TPS2552 is not connected to ground.On your big board from the zip file, there is no need to make the copper pour on the bottom smaller than the board. Best to led it flow on the whole bottom equally.There is a lot of space on the board that allows for better placement of the components, making routing more optimal.

author: Yunadex
author_rank: Contributor
timestamp: June 03, 2025, 03:59:44 pm
content: yeah there is a lot of wasted space but it's the best my beginner brain can manage i plan to practice and learn moreoverall not horrible i can correct the other errors and make it copper area instead

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 03, 2025, 04:21:19 pm
content: Look at where I placed the 120uF capacitor that is on VB1. Reduces the amount of impedance between the connector and the capacitor, which decreases the risk on oscillations and noise.I named that net VB1 to make it easy to assign a copper area to it.

author: Yunadex
author_rank: Contributor
timestamp: June 03, 2025, 04:44:10 pm
content: tadaa?i made it a lot more space optimized and moved the capacitor( don't mind the 5V and Ground layer not being there )

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 03, 2025, 04:52:21 pm
content: Better. But the copper area for VB1 can be smaller to get rid of some artifacts. Look at how it is on my design.Also take notice of the markings on the silk screen. When packing things so close together, make sure not to have markings on the solder pads and put the component names in a logical and readable place. You can reduce the size of the text. I use 35mil for the text. Yes, I'm old school and used to working with mils when doing PCB design.

author: Yunadex
author_rank: Contributor
timestamp: June 03, 2025, 05:00:22 pm
content: think that about does it?

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 03, 2025, 05:06:59 pm
content: Now make it a bit wider on the right side such that the via for the CC signal is enclosed in the copper. This way there is a better current path for the right supply pin.Edit: As a side note, check the component footprints against the datasheets, especially for the USB-C connector. The through holes for the ground attachment pins should be oval, for what I saw of it. Just make sure that the holes are big enough to fit the pins.

author: Yunadex
author_rank: Contributor
timestamp: June 03, 2025, 05:10:48 pm
content: oh yeah totally overlooked that thanks! think that about does it, then just copy paste 10 times and add the barrel jack thing i turned into a module, helllllll yissss thank you so much! think i learned a lot :3

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 03, 2025, 05:32:30 pm
content: To avoid wasting money, you might want to consider a first prototype with just one port to see if it actually works as intended.

author: Yunadex
author_rank: Contributor
timestamp: June 03, 2025, 05:59:52 pm
content: Yeah ill do that when i can afford it currently I'm too poor for even one xD but got some stuff up on marketplace so that'll pay for it when it sells

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 03, 2025, 06:16:57 pm
content: That gives you time to read all the datasheets and the USB-C specification and review your design.