hybridfree/eevblog-posts huggingface dataset:
USB-C PD with fluctuating power supply? - Page 1
Forum section: electronics / projects

author: rs20
author_rank: Super Contributor
timestamp: February 18, 2020, 02:46:19 am
content: So I'm familiar with the idea that if you have a practically limitless supply of power ( > 100W at all times in this context, e.g. mains power or a well-charged lead acid battery), then you can use a chip likeSTUSB4700, optionally configure it for whatever limits you want to impose, and you're good to go -- you get a USB-C 'power supply' that can provide up to 100W to a phone or laptop, depending on how much the laptop/phone wants to pull. This is all fine.What I'm wondering about is what the best approach to take is when your power supply is highly variable in terms of how much power is available -- e.g., a solar panel, human-powered hand crank, etc. Ideally I could just dump the energy into the Vbus line, clamping the voltage to 19.5V or whatever the present limit is, and the phone would detect a sag in voltage well below 19.5V as a signal that it should reduce current consumption. But that would be a "breach of contract" on the part of the power supply, and I believe the STUSB4700 would detect the undervoltage and trigger an error. So that would probably end up with the phone being charged in some sort of horrible hiccup mode or something undesirable like that. But maybe it would be fine?I could update the configuration in the STUSB4700 multiple times per second, have enough storage just for a few seconds of power, and the device could retrieve the new settings and modulate its input accordingly. But I highly doubt that would work; I assume the device would assume that the power supply won't regularly "change its mind" on how much power it can supply.I could probably regularly reset the device's USB or PD data lines to force a re-retrieval of the up-to-date limits, but would the charging process get interrupted?In short, I'm really not sure what the best way to modulate the consumption of the phone/laptop is, since the whole arrangement seems to be optimized for allowing the load to determine how much power it consumes. Any suggestions would be most greatly appreciated! The dream is an arrangement where the generated power is going straight into the phone/laptop's battery, even though it's varying greatly over time.
USB-C Power & Charging. - Page 1
Forum section: electronics / projects

author: nbritton
author_rank: Frequent Contributor
timestamp: November 05, 2016, 05:36:53 pm
content: Anyone have any insights into how USB-C handles power and charging? For instance, on the new MacBook and MacBook Pro? I'm trying to figure out if I can charge one of these from a battery bank. I have a 18650 battery bank that is capable of outputting 3.6, 5, 6, 9, 12, 15, 16, 19, or 21 volts. If I had a barrel plug to USB-C adaptor could I charge off of this?Here is a link to the battery bank that I have:https://www.aliexpress.com/item/3-6V-5V-6V-9V-12V-15V-16V-19V-21V-output-mobile-notebook-power-bank-box/32236605150.html?spm=2114.13010608.0.0.H2KMPk

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 05, 2016, 07:39:02 pm
content: There's a rather complicated protocol to enable voltages above 5V. Probably the easiest solution is to get a USB-C car adapter and connect it to the 12V output.

author: ericloewe
author_rank: Unknown
timestamp: November 06, 2016, 12:44:44 pm
content: USB Power Distribution isn't something you can hack together, unlike all the weird and wonderful charging methods that proliferated before.The cable you're using needs an ID chip, to negotiate cable capabilities, then the supply needs to speak USB-PD (It's implemented over I2C), which tends to imply an off-the-shelf USB-PD controller, which needs to interface with the actual supply to provide adequate voltage.I don't think MacBooks and other laptops charge from 5V supplies, but for smaller devices that do (phones, mostly, at this stage), you can just use more traditional USB charging methods (A certain resistance value across the data terminals of a USB 1.0/2.0 connector) along with a USB Type-C to USB Type-A cable. For cost-efficiency reasons, these cables don't need any chips in them, they're identified by a 56k (IIRC) resistor across certain pins of the USB Type-C plug. For obvious reasons, this is limited to +5V supplies.

author: ericloewe
author_rank: Unknown
timestamp: November 06, 2016, 07:55:10 pm
content: Quote from: blueskull on November 06, 2016, 12:50:11 pmApparently, they don't. It's surprising, given their standards-hostile attitudes, but they say it charges from any USB PD-compliant charger (assuming it's powerful enough, of course).https://support.apple.com/en-ae/HT204360More impressively, it even seems to charge from 5V supplies after all. I've seen several sites talking about using USB battery packs to charge them, so it should be possible to just set the output to 5V and indicate the maximum safe current with whatever resistance value is needed in the wild west of USB charging.
USB-C power problem - Page 1
Forum section: electronics / projects

author: crgarcia
author_rank: Regular Contributor
timestamp: May 08, 2022, 05:50:38 pm
content: Full project documentation/layout/schematics/etc:linkI had this design that worked fine with Micro USB (full schematics)I now replaced it with an USB-C (full schematic)When I connect an USB-C, the voltage drops almost to 2 volts (sorry for the img quality, rigol software stopped working)The current seems to fluctuate between 20mA and 40mA (measured with a multimeter)If I connect an external bench power supply to the 5V line, then it works fine, and current reaches around 80mA.I am a bit lost on how to troubleshoot this...Do you know what could be wrong?Any ideas on what I can try out?Thank you!

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 09, 2022, 02:39:26 am
content: Connect shield and ground just as it was done for the micro USB. I also assume you ruled out a defective connector or defective cable?

author: crgarcia
author_rank: Regular Contributor
timestamp: May 10, 2022, 06:45:45 am
content: Thank you very much evb149 and NiHaoMike!!I found the problem:The guilty one is the 50 Ohm resistor I added to the VBus (5V+) to limit inrush current. I placed it there because I have too much capacitance (> USB documented limitations)Now I replaced the resistor by a 0Ohms and now everything works.Thanks!

author: pigrew
author_rank: Frequent Contributor
timestamp: May 10, 2022, 05:01:16 pm
content: Quote from: crgarcia on May 10, 2022, 06:45:45 amYep... it gotta be between 1 and 10 uF.My solution is usually putting a "soft-start" load switch (permanently turned on), which often has a side-benefit of integrating overcurrent protection.

author: jbb
author_rank: Super Contributor
timestamp: May 10, 2022, 09:53:24 pm
content: You can also get switch ICs with over voltage protection, which is helpful.One thing to keep an eye on is cable plugging - the cable has a little inductance and can form a resonant network with input caps. This can turn a 5V input into an 8V peak or more.TVS diodes are of limited use there - you need around a 6V device, and it seems they can be relied on to reliably clamp at approximately 1.5x rating, ie 9V.There are dire rumours around of non-compliant “USB” wall chargers that simply spit out 20V all the time.
USB-C powered soldering iron - Page 1
Forum section: electronics / projects

author: LapTop006
author_rank: Unknown
timestamp: February 23, 2017, 11:25:27 am
content: Today's (yesterday's now) evil project was inspired by a suggestion after my talk on USB-C & USB-PD at this years's linux.conf.au Open Hardware miniconf.Using a knock-off Hakko driver and handpiece I've created what may be the first USB powered soldering iron that doesn't suck (ok, it's not a great iron, but at least it has sufficient power to be usable).Building this was actually trivial, I just wired the 20v output of one of my USB-C ThinkPad boards to a generic Hakko driver board, the loss of power from using 20v not 24v is noticeable, but for small work this would be fine (I solder in either the work lab or my home lab, where both have very nice soldering stations so I don't actually expect to ever use this).If you were to turn this into a real product you could in fact do much better, by doing both power negotiation and temperature control in a single micro, the driver could instead be switched to a boost converter instead of just a FET, and by controlling the output voltage control the power draw, and simply disable the regulator to turn off the heater. By chance, the heater resistance of the Hakko 907 clone handpieces is such that combined with USB-PD power rules you'd always be boost converting, never needing to reduce voltage.With such a driver you could run this from anything starting with a 5v USB-C phone charger or battery (15W for the nicer ones), 9v at up to 3A off some laptops (for ~25W), or all the way to 20V@5A for those who need an extremely high-power iron. 60W, which happens to be the standard power level of many good irons (such as the Hakko FX-888D) is also at 20v@3A a common limit for chargers (and also many cables, only fixed cables, or those specially marked with an ID chip can go all the way to 5A). As higher power USB-C batteries start becoming available for laptops this becomes a real option for on-the-go use.Here's a photo of it running from a Chromebook Pixel charger:1:http://www.openhardwareconf.org/wiki/OHC20172:http://laptop006.livejournal.com/59323.html

author: amyk
author_rank: Super Contributor
timestamp: February 23, 2017, 11:52:10 am
content: Even a 5V USB iron can be usable for small joints, although it isn't a 936-style handle:
USB C routing:  Will this work? - Page 1
Forum section: electronics / projects

author: hermitengineer
author_rank: Regular Contributor
timestamp: April 22, 2024, 05:10:45 am
content: I just switched from micro-USB to USB-C. It's still 2.0 (actually even 1.0 compatible) and will only be using "full speed". Should the routing shown below be within tolerance for track length?

author: semir-t
author_rank: Regular Contributor
timestamp: April 22, 2024, 07:00:55 am
content: Did this a lot of times and never had an issues. It is short distance for it to take an that much effect on the signals.Just make sure that you have ground plane beneath the traces all the time.

author: tszaboo
author_rank: Super Contributor
timestamp: April 22, 2024, 07:58:40 am
content: Full speed is 12 megabit. You can run one of the signals through a coat hanger and it would probably work.

author: hermitengineer
author_rank: Regular Contributor
timestamp: April 23, 2024, 04:14:37 am
content: As it turns out, you're probably right

author: SiliconWizard
author_rank: Super Contributor
timestamp: April 23, 2024, 05:34:48 am
content: Yes.But even HS would be fine with this routing. (Probably not with the coat hanger!)

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 23, 2024, 06:16:02 am
content: Coat hanger wouldn't pass EMC by any means, but signal quality would be perfectly cromulent for Full Speed. It might even work for High Speed, but I think you would at least need to make it a parallel-lead transmission line by then.Tim

author: jkostb
author_rank: Regular Contributor
timestamp: April 23, 2024, 04:39:49 pm
content: Do you have a ground reference plane below the USB signals? I don't see this. USB signals should be routed as differential pair controlled impedance lines. So you need a ground reference plane below. Also the ground pour besides the USB signals changes the controlled impedance. I still see a lot of layouts where the top and bottom layers are poured with ground. Often without stitching vias. People think that it will help against EMI issues and signal integrity. The contrary is the case.

author: hermitengineer
author_rank: Regular Contributor
timestamp: April 24, 2024, 04:06:27 am
content: You are correct that this is a 2-layer board. The ground pour on the bottom is as complete as it can be and does have connection between parts, but it is partitioned by bottom layer vertical tracks.If I have a need for high or super speed, I'll keep grounding and impedance in mind though.
USB Cable wire specification? - Page 1
Forum section: electronics / projects

author: ShinyPCB
author_rank: Newbie
timestamp: October 11, 2020, 04:27:45 pm
content: Hi All,Have an electronic interface using a serial (FTDI232RL) USB connection. Looking to get USB cables to connect it to a phone or tablet of no more than a metre long using a USB-C or USB-Micro connection. What AWG specification would you consider needed for the cable? Would 28AWG suffice for both data pair and voltage?Thanks

author: HB9EVI
author_rank: Frequent Contributor
timestamp: October 11, 2020, 04:35:12 pm
content: that's not only a question of AWG but one of the cable impedance, which ist 110for USB. For short distance and full speed USB (12mbit/s) it's rather unimportant, but for longer cables with hispeed (USB2/480mbit/s) or superspeed (USB3) impedance matching of the cable is essential.

author: reboots
author_rank: Regular Contributor
timestamp: October 11, 2020, 05:37:34 pm
content: Is the device powered over USB? If so, depending on how much current it draws, heavier gauge (24/26 AWG) would be better. If not, any cable should work.Are you building the cable, or buying an off-the-shelf assembly? Many USB cables advertise heavier conductors for power. This one claims 30 AWG for data and 22 AWG for power.https://smile.amazon.com/dp/B018RAW1FG

author: ShinyPCB
author_rank: Newbie
timestamp: October 11, 2020, 06:35:31 pm
content: The device gets its power from another source so power load is not significant.On a standard PC connection 28AWG for data and 24AWG for power is suffice. Was wondering whether the same would be needed for connection to tablets/phones?

author: reboots
author_rank: Regular Contributor
timestamp: October 11, 2020, 07:10:26 pm
content: I see. Yes, the application is essentially unchanged. The 28+24 AWG cable would be fine.
USB Charger Reverse Connection Protection - Page 1
Forum section: electronics / projects

author: catalyst
author_rank: Contributor
timestamp: September 25, 2018, 08:12:07 am
content: Hi,I have designed a USB Charger for busses. We assume that a person may do a short circuit by using metal pen or tweezers etc. Because automotive a place that has very vandalism. I have to think anti-vandal solution for this. Because USB connectors are fragile to bad external factor. Do you have any suggestions for me? How can i protect USB connector by using a component or etc. For example, a diode may be acceptable but, diode's threshold voltage will decrease my USB voltage(5V) and this effect will affect my charge performance.Thank you for answering.

author: Mr. Scram
author_rank: Super Contributor
timestamp: September 25, 2018, 08:23:56 am
content: Quote from: catalyst on September 25, 2018, 08:12:07 amMaybe you could use a diode between the rails and have a 1K resistor on 5V and neutral to keep current from flowing that way under reverse conditions? Though if you want to do it nicely, it'd probably be a good idea to use a transistor. That way you'll barely have a voltage drop.http://www.electroboom.com/?tag=reverse-polarity

author: Jeroen3
author_rank: Super Contributor
timestamp: September 25, 2018, 09:15:42 am
content: One of those power switches from Micrel. (Microchip)MIC2505for example.

author: catalyst
author_rank: Contributor
timestamp: September 28, 2018, 07:19:56 am
content: Hello, I solve the problem which is related to reverse connection. Now, I face a short circuit problem at the output of USB connectors. For example, If someone touches a conductive material between +5V and GND pins, TS30042 explodes unfortunately. I have a solution, use a fuse. But if I use a fuse at 5V, its voltage dropout decrease the 5V to 4.9V. This can be a problem for charging. What can I do for this problem?Thank you for answering.

author: Fabse77
author_rank: Newbie
timestamp: September 28, 2018, 08:57:07 am
content: Hi,I would suggest using a polyFuse. There are models especially for 5V usb and chargersFox example take a look at this low resistance ones:http://m.littelfuse.com/products/resettable-ptcs/low-resistance.aspx

author: Jeroen3
author_rank: Super Contributor
timestamp: September 28, 2018, 09:20:49 am
content: Raise the output voltage to 5.2V, like all typical USB chargers. The fuse, connector and cable add voltage drop.
USB charger/supply - tips needed - Page 1
Forum section: electronics / projects

author: kaning
author_rank: Newbie
timestamp: August 05, 2014, 03:53:15 pm
content: Hi all, this is my first post on the forum and visit although im big fan of eevblog and its always my first option of research most of the times.Overall view: So, im building a portable speaker fed by internal li-po battery wich will pass through a 5v step up to supply audio amplifier PAM8403. Maybe also it will have bouetooth but thats not important for now. This internal battery will be charged through usb port. An its here where i need some guidance.How to plan the schematic of this particular part? when battery is charged, it feeds all circuit; when battery is empty and i plug USB it feeds circuit and charges battery and ofcourse doesnt need pass through step up anymore.General purpose question is:what kind of circuit, IC should be used when you have some project fed by internal battery and you want to charge it via USB while On, so it charges battery and supply circuit??(as we see in pretty much portable device(mp3,phone,laptop etc? many thanks in advance

author: RiverTown
author_rank: Regular Contributor
timestamp: August 05, 2014, 03:58:05 pm
content: http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en536670Other manufacturers have similar ICs..

author: kaning
author_rank: Newbie
timestamp: August 05, 2014, 05:15:50 pm
content: Actually this is exactly the IC im using :b and i already used couple of time, i just never saw this particular thing in datasheet "Integrated System Load Sharing and Battery Charge Management". So a parallel connection such as this below would be enough?If so i apreciate because i didnt knew about this feature. Anyway, it seems a litle bit inneficient since usb already has the 5v i need for the rest of the circuit so its a waste of energy regulating it to 4,2v and then step it up to 5v again. :/Im looking for a solution that would make circuit work something like this on the presence of USB port connectionOr im thinking wrong here? maybe im missing something here.. many thanks

author: mikerj
author_rank: Super Contributor
timestamp: August 05, 2014, 07:50:20 pm
content: Check the "Typical Application" schematic on page 27 of the data sheet. Pins 1 and 20 would be connected to your 5v step-up switcher and the chip internally selects from either the USB supply or the lithium ion cell.

author: kaning
author_rank: Newbie
timestamp: August 06, 2014, 01:24:36 pm
content: what datasheet? what pin 1 and 20?mmaybe you forgot to mention IC or something else. thanks

author: tjb1
author_rank: Regular Contributor
timestamp: August 06, 2014, 02:13:14 pm
content: Quote from: RiverTown on August 05, 2014, 03:58:05 pmhttp://ww1.microchip.com/downloads/en/DeviceDoc/20002090C.pdfQuote from: kaning on August 06, 2014, 01:24:36 pm
USB current negotiation without Power delivery, the easy way - Page 1
Forum section: electronics / projects

author: satyamfifa
author_rank: Regular Contributor
timestamp: July 15, 2023, 01:31:58 am
content: Hey All,Out there on the internet search results are saturated with power delivery on USB C, and there are many chips avaiable to do this the easy way such as STUSB4500, but what if the device gets connected to a host that doesn't have power delivery (without CC pins), how can it negotiate for more current such as 500 mA specified by USB 2.0 or 900mA / 1.5 A or 3 A specificed by USB 3.1, are there any chips avaialble to do this? That is without having to run a USB stack on PIC32 od STM32?Regards,Sparsh

author: satyamfifa
author_rank: Regular Contributor
timestamp: July 15, 2023, 02:20:54 am
content: I found a hynetek husb238

author: igor78
author_rank: Contributor
timestamp: July 16, 2023, 01:28:21 am
content: Afaik you can only hack it to give 3ASearch internet for usb-c 5v 3A hackhttps://forum.digikey.com/t/simple-way-to-use-usb-type-c-to-get-5v-at-up-to-3a-15w/7016

author: ve7xen
author_rank: Super Contributor
timestamp: July 17, 2023, 07:14:59 pm
content: USB Battery Charging Specificationdefines 3 types of ports that can be identified without / before enumeration:Standard Downstream Port (non charging port) - strictly speaking, no more than 100mA should be drawn without enumerating, but it is probably safe to pull 500mA or moreCharging Downstream Port - a port that supports USB data and also charging enumerationDedicated Charging Port - a port that doesn't support USB data, but does support charging enumeration (e.g. a dedicated charger)Detection works by sourcing a small voltage on D+ and sinking a small current on D-. I don't know if there are chips dedicated to this, probably.If a charging port is detected, then up to 1.5A can be drawn at 5V.If you need higher voltages or currents, then you need to use one of the nonstandard 'quick charge' protocols.

author: wraper
author_rank: Unknown
timestamp: July 17, 2023, 07:30:10 pm
content: QuoteThe easy way is to not negotiate at all. 99.9% of USB hosts will supply at least 500mA current anyway even though standard says you must request it. Otherwise you need to implement a real USB peripheral with USB VID and PID.
USB data mux - bi-directional? - Page 1
Forum section: electronics / projects

author: jmulder88
author_rank: Newbie
timestamp: September 23, 2021, 08:21:38 am
content: Just trying to put together a small USB switch for my own educational purposes and I am struggling a little with choosing an appropriate multiplexer for the D+ and D- lines.My situation is that I want to be able to share a single USB port with 2 PCs, with the press of a button I want to be able to disconnect the USB port from one machine then connect it to the other. For this I am using a power mux for the +5v lines from the 2 machines and a USB mux for the data lines.I found theFSUSB20andFSUSB30muxes but I can't choose which one is more suitable. For a start they both seem to be a DPDT switch, fine - that's what I am after, but:The FSUSB20 sells itself as "bi-directional", the FSUSB30 makes no mention of that. Is this important?The two ICs use different nomenclature for the pins, not sure if it's relevant or not?The FSUSB20 is described as "1 port" whereas the FSUSB30 is "2 port". Why is this? They appear to be logically identical to me? Is this to do with the bi-directional thing?Can someone help me choose what is the best out of these for my purposes? Or indeed recommend an alternative IC if neither of these are any good. The FSUSB30 is easier to get for me, but I was especially thrown out by the lack of "bi-directional" in the datasheet so wanted to make sure I was doing the right thing. Thanks!

author: moffy
author_rank: Super Contributor
timestamp: September 23, 2021, 08:33:10 am
content: They both do the same thing, the FSUSB30(not USB3 compatible, just USB2) has some extra protection circuitry, page 1. So I would tend to lean towards that one. They are both bidirectional because they are analog switches.
USB Data Only for data acquisition ('scope) - Page 1
Forum section: electronics / projects

author: theoldwizard1
author_rank: Regular Contributor
timestamp: August 28, 2016, 02:07:49 am
content: In order to minimize "noise", is limiting power(likely not used anyway)and ground between the "host" computer and the data acquisition device a good or bad idea and why ?To keep it simple, let's limit the discussion to USB 2.0.

author: singapol
author_rank: Frequent Contributor
timestamp: August 28, 2016, 05:25:22 am
content: Actually it's a wide ranging subject touching on circuit design and layout and hardware (power supply).It is well known anything PC related is noisy despite the hype in terms of data acqusition. It is analog signal in real life. Depending on the type of signal small or large aquired using a linear supply saves you headaches.Then take the chance as it gets to PC unmolested.In theory having host PC and data acquisition device on same ground is prefered as the ground noise is referenced to same ground. For a more detail treatmenttry to download an old copy of Henry Ott's Noise Reduction Technique in Electronic Systems 2nd. edition.There are tons of articles on noise online.

author: theoldwizard1
author_rank: Regular Contributor
timestamp: August 28, 2016, 06:46:04 pm
content: Quote from: blueskull on August 28, 2016, 05:26:47 amExcuse me but how does a "couple of volts" wind up on a differential serial bus ? I thought the whol point of a differential transceiver was to isolate it from power and ground ?

author: Ian.M
author_rank: Super Contributor
timestamp: August 28, 2016, 07:16:19 pm
content: USB isn't fully differential. It uses a single ended zero state (SE0) with both lines low for various signalling purposes. As such it cant tolerate any significant difference in 0V potential between the device and the host.

author: David Hess
author_rank: Super Contributor
timestamp: August 28, 2016, 10:02:54 pm
content: Noise is usually less of a problem than destructive overload. Accidentally connect the probe ground of your USB instrument to AC hot (or AC neutral if the neutral connection fails) and you may end up replacing the PC and various devices attached to the PC.
USB device Vbus capacitance - Page 1
Forum section: electronics / projects

author: michaelym
author_rank: Regular Contributor
timestamp: May 12, 2014, 01:59:55 pm
content: It says the USB application note AN0046 for EFM32WG that the capacitance on Vbus in device configuration must be lower than 6.5uF.Why? what would happen if it would be higher? how high can it be without being catastrophic?I need to set up the USB as OTG i.e. both device and host and for host I need at least 90uF.

author: Jeroen3
author_rank: Super Contributor
timestamp: May 12, 2014, 02:51:25 pm
content: Because the standards says so.QuoteChapter 7.2.4.1 Inrush Current Limitingof USB 2.0.*100 mAThe standard is free, read it
USB differential pair on 2 layer board - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: January 16, 2019, 11:17:20 am
content: I realize a 2 layer board is less than ideal for this, however that's what were stuck with for this application.I'm laying out a board that will make use of an open source Arduino board for the uC section, because the code is already written and tested on the MkrZero board. I imported the PCB files and when I perused the USB differential pair, first thoughts are this is not right. Trace width is 0.25mm (9.84 mils), and space is 0.2mm (7.87 mils). This is a 1.6mm board. Assuming FR-4Viewed as an edge coupled external plane, Zdiff =148However, both the top an bottom are flooded with ground plane as shown.Viewed as a coplanar waveguide, Zo is close to 90, not sure about Zdiff?Looks like I need a more versatile calculator.Is this just a compromise, the total length is only about 37mm (1.5"), or does the top flooded plane significantly lower Zdiff?PCB house tells me to send it and they will tweak as required, however for 90based on edge coupled, the trace width would need to be closer to 40 mils and that's neither a tweak or feasible.

author: martin1454
author_rank: Regular Contributor
timestamp: January 16, 2019, 11:33:21 am
content: If you can - Use a 0.8mm PCB instead of 1.6mm, that will make it easier to approximate the 90 Impedance - Use as thick traces as possible, and be aware that if you let the ground pour on the top layer get too close, it will also alter the impedance

author: Rerouter
author_rank: Super Contributor
timestamp: January 16, 2019, 11:35:14 am
content: usb on a 1.6mm thick board always calls for crazy thick traces, instead focus on keeping the distance you need to route your USB lines short, this way you dont need to worry about impedance anywhere near as much,you can reduce how much trace width you need a bit by routing a picketed ground along side the differential pair. (coplanar Wave differential pair, its not in any free tool I have seen, but you can use it to trim down your Zo)If you want to follow the spec as close as possible, 0.18mm gap, 0.8mm trace, 0.8mm gap to ground, yes it is crazy sized, and near to the ratio limits, but if you want close to 90 diff, 50 Zo, then that should put you inside the limits.A good tool for this is "Saturn PCB Toolkit"

author: martin1454
author_rank: Regular Contributor
timestamp: January 16, 2019, 01:04:44 pm
content: Also a small note - You will probably use USB 2.0 low speed mode, and not high speed mode, which means the impedance is not that important (compared to high speed at least) but still aim for the best possible impedance.

author: Jester
author_rank: Frequent Contributor
timestamp: January 16, 2019, 02:36:02 pm
content: Any comments on the apparent 150Zdiff on the Arduino board? It obviously works.Wild guess as to how much the top ground plane helps?When you say short, how short is short? If less about 1" and no expectation beyond USB 2.0 speed is this a reasonable compromise?
USB Dongle Reader Chip(s)[SOLVED] - Page 1
Forum section: electronics / projects

author: jpanhalt
author_rank: Super Contributor
timestamp: October 09, 2025, 03:51:52 pm
content: Has anyone here opened up a Versalent WLKB232 that is sold to directly read a USB dongle from a wireless keyboard/number pad? The MCU or other chip (like a MAX3421E) are not identified in the operator's manual.Edit: There's a PIC24 inside with USB plus the chips already described in the manual for it.
USB ECN for 5.5V VBUS? - Page 1
Forum section: electronics / projects

author: rounin
author_rank: Regular Contributor
timestamp: May 01, 2019, 09:00:24 pm
content: I downloaded the USB 2.0 spec from here today,https://www.usb.org/document-library/usb-20-specification,and found a "USB ENGINEERING CHANGE NOTICE, USB 2.0 VBUS Max Limit" that says VBUS may now be as high as 5.5V as part of some changes for type C.This worries be a bit, I just did a device with a 5.5V max LDO, thinking since we protected it and slew limited the inrush it would be plenty of margin.Is this real? Any devices in the wild with a higher VBUS than 5.25V?

author: rounin
author_rank: Regular Contributor
timestamp: May 01, 2019, 09:05:31 pm
content: http://www.testusb.com/power_issue.htmmentions testing up to 5.5V. Maybe the general population (eg wikipedia) is just out of date when listing VBUS max as 5.25V.
USB Emulator to replace FLoppy in older HP Equipment??? - Page 1
Forum section: electronics / projects

author: watchmaker
author_rank: Unknown
timestamp: September 29, 2025, 12:18:31 am
content: Has this been done with success? Here is one I have in mind:https://www.amazon.com/dp/B0762NCHC6/?coliid=IZTK4IN187EXM&colid=1EVVXWR1VYVYY&ref_=list_c_wl_lv_ov_lig_dp_it&th=1THANKS!!

author: ledtester
author_rank: Super Contributor
timestamp: September 29, 2025, 05:51:33 am
content: Have a look at this site:https://hxc2001.com/If you look at their compatibility list:https://hxc2001.com/download/floppy_drive_emulator/support.htmand under Test/measurement/...:https://hxc2001.com/download/floppy_drive_emulator/support.htm#HXC_COMPATIBILITY_TABLE_MISCyou will see all of the old HP equipment the device supports.There seems to be two ways to go with this company:- buy the HxC Floppy Emulator -- a hardware device- buy a firmware upgrade for the Gotek emulator units:https://hxc2001.com/docs/gotek-floppy-emulator-hxc-firmware/Also, there is a free alternate firmware for the Gotek device here:https://github.com/keirf/flashfloppyand others have configured that firmware to interface with older Tektronix equipment:- "Tektronix Curve Tracer Modification: Mass Storage Conversion to USB Memory Device"https://apps.dtic.mil/sti/trecms/pdf/AD1149323.pdf-https://github.com/andrewpono/TDS3000-Series-Gotek-FlashFloppy

author: watchmaker
author_rank: Unknown
timestamp: September 29, 2025, 11:07:23 am
content: Thank you!
USB endoscope and Garmin nuvii - Page 1
Forum section: electronics / projects

author: raidencmc
author_rank: Newbie
timestamp: October 18, 2016, 10:04:13 pm
content: I have a Usb endoscope and an old garmin nuvi 255w. I am wondering if there is some way to connect the 2. I would imagine that the endoscope produces some sort of video signal when connected to a voltage from the usb source. Can you cut the usb cable and take that signal and connect it somewhere inside the garmin. And if so how do I figure out that connection point?Sent from my VS985 4G using Tapatalk

author: jeroen79
author_rank: Frequent Contributor
timestamp: October 19, 2016, 10:39:10 am
content: USB is a digital serial interface, it does not contain 'some sort of video signal' by itself.Likely it will present itself as a camera to the USB host it is connected to.If that host is programmed to recognize a cameradevice then it could use the videodata sent from the camera.Note that I mentioned 'USB host', this is a specific role within the USB scheme.Normally peripherals (such as a camera or gps) will take the role of 'device'.Unless they have a female USB A port (as on your PC) or they are advertised as having host or OTG capability you likely cannot plug the camera into the garmin gps and expect it to work.And you'd have to reprogram the garmin as well.But if you're up to that challenge and don't mind voiding the garmin's warranty then you could probably put a microcontroller in between the endoscope and the garmin.To find out _where_ you could connect things on the garmin you would have to see what is inside and then study the datasheets for the relevant processor/controller.It may have some free gpio/serial/i2c/etc ports.

author: raidencmc
author_rank: Newbie
timestamp: October 22, 2016, 08:18:52 pm
content: Ok that is a little bit above my ability. Thanks for the help.Sent from my VS985 4G using Tapatalk
USB Flash Memory Controller ICs? - Page 1
Forum section: electronics / projects

author: TheAdmiralty
author_rank: Contributor
timestamp: May 28, 2020, 07:57:48 pm
content: Not sure where this one belongs so I'll drop it here for now.What's going on with the purchasing requirements for basically any USB flash media controller (like you'd see on a thumb drive)? I've never noticed this before either at work or for a personal project because I've never had need of one, but I can't even find a contact point at any of the manufacturers or distributors to ask about them. It looks like Microchip has a couple eMMC/similar controllers but those aren't really what I'm talking about here.Not much else to say... I see a few on eBay from China but that's it, and those aren't really useful to me without a datasheet. Is literally every USB flash interface NDA'd, or is this something with USB-IF licensing again?...
USB Ground Isolator - Page 1
Forum section: electronics / projects

author: Smash54
author_rank: Newbie
timestamp: August 27, 2019, 04:56:38 pm
content: Hello AllI have a question maybe someone can help me out with about a Ground Loop hum I am experiencing. I have a Scarlett Solo Guitar Interface connected to my PC via USB cable outputted to a Tube amp. With the Amp grounded I get a 60 cycle hum if I lift the Ground on the Amp it goes away but don't want to leave it that way. I have tried those small dongle USB Ground loop isolators on Amazon but they won't allow the PC to power the Scarlett. What I was thinking was to do something with the ground wire on the USB Cable seen somewhere someone using 2 Diodes and a Resistor to isolate the ground looks like it would work any Ideas.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: August 27, 2019, 05:00:39 pm
content: You need one with a 5V/5V isolated DC/DC. Made some myself some time ago, but you can also buy something like that:http://lemmini.de/USB%20Isolator/USB%20Isolator.html

author: fourfathom
author_rank: Super Contributor
timestamp: August 27, 2019, 05:28:01 pm
content: Or look into a 1:1 audio coupling transformer between the amp and the interface. This will break any ground loop.

author: Smash54
author_rank: Newbie
timestamp: August 27, 2019, 07:44:31 pm
content: Thank you
USB -> 9V Stepup with short circuit protection and 500mA Input current limit - Page 1
Forum section: electronics / projects

author: luky315
author_rank: Regular Contributor
timestamp: September 10, 2012, 08:14:52 am
content: I'm looking for a solution to get 9V out from USB with short circuit protection and 500mA current limit to comply with the USB Specs.I haven't a good solution yet. I found a few Stepup-converter with input current limit (LT1618) and output Voltages > 6V, but they have a problem when the output is shorted or when a big capacitive load (1000µF) is connected.Should I add an aditional   High-side Switch with short circuit protection or is there another solution?

author: kripton2035
author_rank: Super Contributor
timestamp: September 10, 2012, 08:32:07 am
content: max1896 can be a good candidate ?http://www.maximintegrated.com/datasheet/index.mvp/id/3184regards,

author: luky315
author_rank: Regular Contributor
timestamp: September 10, 2012, 09:03:22 am
content: The MAX1896 has soft-start, but I don't see an adjustable Current limit and Short circuit protection function.

author: Christopher
author_rank: Frequent Contributor
timestamp: September 12, 2012, 05:23:47 pm
content: Poly fuzeEEVBlog has a simple soft-start vid with a couple fets somewhere

author: hlavac
author_rank: Frequent Contributor
timestamp: September 14, 2012, 10:56:03 am
content: When you limit input current to a dcdc converter you limit output current by it automatically.What are you trying to do? Limit current from huge output cap??
USB HID Battery System Report descriptor - Page 1
Forum section: electronics / projects

author: Aggressive_Doughnut
author_rank: Contributor
timestamp: January 16, 2021, 08:56:27 pm
content: Hey all. Anyone ever write an HID report descriptor for a "battery system"? I'm trying to add one on to a generic joystick I made (works great) to report battery level, but I cannot get it to function correctly. I've tried a bunch of different variations on the Appendix A example from the USB HID power devices spec, but no good. Right now this is my basic model that I keep trying to get to work, so suggestions are very welcome:Code:char ReportDescriptor = {0x05, 0x85, // USAGE_PAGE (Battery System)0x09, 0x18, // USAGE (BatteryInsertion)0x75, 0x01, // REPORT_SIZE (1)0x95, 0x01, // REPORT_COUNT (1)0x15, 0x00, // LOGICAL_MINIMUM (0)0x25, 0x01, // LOGICAL_MAXIMUM (1)0xb1, 0x03, // FEATURE (Cnst,Var,Abs)0x09, 0x2c, // USAGE (CapacityMode)0x75, 0x01, // REPORT_SIZE (1)0x95, 0x01, // REPORT_COUNT (1)0xb1, 0x03, // FEATURE (Cnst,Var,Abs)0x75, 0x06, // REPORT_SIZE (6)0x95, 0x01, // REPORT_COUNT (1)0xb1, 0x03, // FEATURE (Cnst,Var,Abs)0x09, 0x83, // USAGE (DesignCapacity)0x75, 0x18, // REPORT_SIZE (24)0x95, 0x01, // REPORT_COUNT (1)0x67, 0x01, 0x10, 0x10, 0x00, // UNIT (SI Lin:Battery Capacity)0x55, 0x00, // UNIT_EXPONENT (0)0x15, 0x00, // LOGICAL_MINIMUM (0)0x27, 0xfe, 0xff, 0xff, 0x00, // LOGICAL_MAXIMUM (16777214)0xb1, 0x03, // FEATURE (Cnst,Var,Abs)0x09, 0x66, // USAGE (RemainingCapacity)0x75, 0x24, // REPORT_SIZE (36)0x95, 0x01, // REPORT_COUNT (1)0x67, 0x01, 0x10, 0x10, 0x00, // UNIT (SI Lin:Battery Capacity)0x55, 0x00, // UNIT_EXPONENT (0)0xb1, 0x03, // FEATURE (Cnst,Var,Abs)0x09, 0x42, // USAGE (BelowRemainingCapacityLimit)0x09, 0x44, // USAGE (Charging)0x09, 0x45, // USAGE (Discharging)0x75, 0x01, // REPORT_SIZE (1)0x95, 0x03, // REPORT_COUNT (3)0x15, 0x00, // LOGICAL_MINIMUM (0)0x25, 0x01, // LOGICAL_MAXIMUM (1)0x65, 0x00, // UNIT (None)0xb1, 0x03, // FEATURE (Cnst,Var,Abs)0x75, 0x05, // REPORT_SIZE (5)0x95, 0x01, // REPORT_COUNT (1)0xb1, 0x03 // FEATURE (Cnst,Var,Abs)};
USB High Power 3A per port hub based on USB2514B - Page 1
Forum section: electronics / projects

author: Lt_Flash
author_rank: Regular Contributor
timestamp: September 06, 2019, 11:40:46 am
content: Hi guys,Just want to show you my new project that seems to be working quite well. It's a USB2514B-based USB 2.0 High Speed hub with MCU to monitor and control currents, voltages and temperature of the PCB. It's only a double-sided PCB and I know that I'm violating 90Ohm impedance USB requirement with it but it works quite well up to speeds of 40-50MBytes/sec when I'm uploading or downloading data from USB sticks or USB drives. It also supports currents up to 3A per port due to the use of TLV62130 converter. It can get quite hot if all ports are used at 3A, up to 70-80C but handles these currents quite well. MCU used to monitor the circuit and to provide USB2514B with all data necessary via I2C bus is Atmel (Microchip) SAML21E18B. All the data is presented via USART port for now as project is still under development, but later on this would be shown at LCD screen like ST7735 or any other one that uses 3 or 4 wire SPI bus. I believe that 2-layer boards are good enough for such projects and save you a lot of money when designing some not-too-critical USB high speed projects. You can have a look at schematics and board design here:https://workspace.circuitmaker.com/Projects/Details/LtFlash/USB-High-Power-hubPlease let me know what you think about this projects and ask me any questions about it. I'm using Atmel Studio 7.0 in a simplest polled mode to configure USB2514B from SAML21 and then get all the ADC readings for voltages, currents and temperatures. ZXTC1022 is used to monitor current as SAML21E18B doesn't have enough legs to just monitor both sides of a current-measuring resistor, if you use 64 or 100-pin version you can easily get away from using that current monitor. Also, LTC2950 is used just because I wanted to have a possibility of soft switch on-off, it can be removed from the project completely or replaced with a simple switch and MOSFET. Reverse voltage protection is very basic and consists of a P-Channel MOSFET, can also be dropped if you want to save some money. In that case project comes down to USB2514B, TPS562201 to convert voltages from 4.5V up to 17V down to 3.3V to power USB2514B and SAML21, and TLV62130 to power each individual USB port from input 6-17V rail.USB251x is quite useful for any project that has an MCU and some other USB devices, it allows you to create a good 'network' on single PCB that has different USB devices. My project is basically just an example on how to use it and how to monitor all system parameters and represent them either via USB to SAML21, or by USART, or on LCD screen.Thanks!

author: RIKRIK
author_rank: Contributor
timestamp: September 08, 2019, 10:37:06 pm
content: Thanks for posting , interesting project, are you going to go down the hub route, or maybe even a pci header on it, so it could sit inside a computer 👌. That way you don't have to bother with a enclosure .
USB Host and Device Power Circuit - Page 1
Forum section: electronics / projects

author: jwhitmore
author_rank: Regular Contributor
timestamp: March 21, 2016, 05:42:47 pm
content: I've recently learned a great deal on the importance of PCB Layout on a thread I posted on my failing LTC3603 SMPS:https://www.eevblog.com/forum/projects/ltc3603-dc-dc-fails-to-start/As a result I've been re-laying out the design. When looking at this design I sort of wondered if there was a better way of doing my USB Power Section. I'm using a uC which can operate in Host, Device and OnTheGo modes. So I've got a Texas Instruments TPD3S014 chip which is used to turn on power to the USB Port when in USB Host Mode. Because I'm not sure if the TPD3S014 can cope with being powered in reverse I've added D1. As a result of that Diode the voltage coming into the TPD3S014 has to be greater then 5Volts to ensure that ultimately 5Volts is getting to the USB Bus, counteracting the loss through D1.That's USB Host and it's simple enough. So then the other half of the circuit is for USB Device mode, which can either be USB Bus powered or self powered. When self powered the 5V Plus coming from the LTC3603 forces the PNP Transistor Q1 Off and goes through D2. So even if the device operating in USB Device mode and connected to the USB Power no power should be drawn from the USB Bus to the 5Volt rail powering the device.If no power is coming from the LTC3603 then the PNP Q1 is on and the devices 5Volt rail is going to come from the USB Bus.I've looked and I'm sure there has to be a simple single IC solution but I've not been able to find it. So far it's working but is there a better way of doing these three separate functions? Can I get rid of D1? I want to actually take D1 out and see what happens when I connect 5V USB Device Power. If things start to smoke then I'll know.
USB host IC for audio device class - Page 1
Forum section: electronics / projects

author: davegravy
author_rank: Regular Contributor
timestamp: June 15, 2022, 06:44:48 pm
content: I have a USB audio device and want to access its data stream with a MCU via SPI. Is there an IC well suited to this?I know MAX3421E is popular for interfacing MCUs with USB devices but I can't find any projects that have done this for the audio device class.

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 15, 2022, 07:17:49 pm
content: You'll need a MCU with USB host support, which is becoming rather common these days. Look for USB "OTG". (Also define if you need USB HS or just FS, that will narrow your options of MCUs.)With such a MCU, as long as it has an embedded USB PHY (again a lot of choice these days, a bit less for USB HS though), you won't need any extra IC.The "hard" part will be to implement the USB audio class as host. While most MCUs having USB OTG come with a few examples for USB host, those examples usually deal with the simple HID (keyboard, mouse, ...) classes, or the mass storage class. I've never seen vendor-provided libraries/examples implementing the audio class for USB host. That may exist, but specifically look for this.You could alternatively use TinyUSB if the MCU is supported, but I'm not sure TinyUSB supports the audio class for USB host. That'd need to be checked.To sum it up, finding a MCU with USB OTG, either FS or HS depending on your needs, will be easy. The hard part is probably going to be the firmware side.

author: magic
author_rank: Super Contributor
timestamp: June 15, 2022, 09:30:44 pm
content: There is this in the "Demos" directory of the LUFA library for USB capable AVRs.Code:* Audio Input host demonstration application. This gives a simple reference* application for implementing a USB Audio host, for USB Audio devices using* the USB Audio 1.0 class profile.** Incoming audio will output in 8-bit PWM onto the timer 3 output compare* channel A, and will also be indicated on the board LEDs. Decouple the PWM* output with a capacitor and attach to a speaker to hear the audio.It should run on AT90USBxxx series micros with OTG support, there are a few of those, but they aren't very cheap unfortunately.Dunno if Full Speed and Audio Class 1.0 satisfies you.editMAX3421E looks like a fairly universal IC that may be able to handle many USB devices, but 64 byte endpoint buffers will be limiting for audio. UAC (USB Audio Class) device sends/receives a data packet per USB frame (1ms) which packet needs to fit in the endpoint buffer and contain whole 1ms worth of audio samples. With only 64B endpoint buffer you could do no more than 32kHz stereo in 8 bits or mono in 16 bits or up to 64kHz mono in 8 bits.Whether you look for an MCU or an addon chip like the Maxim device, look for endpoint buffers sufficient for the quality you need. Another requirement is support for isochronous transfers.