240W USB-C PD chargers are nearly here, says Framework CEO
theverge.comWill be interested to see if AllThingsOnePlace reviews it, as have been following their particularly in-depth power adapter reviews and their last review[1] of a Framework charger (a 60W model) showed it performed well both in efficiency and other metrics though not the highest performer or value in its wattage range.
Wouldn't ordinarily mention a Youtube channel on HN but felt their detailed testing, comparisons and teardowns would probably be of interest for the topic.
These are exactly the kinds of channels we need more of on YT, I'm glad someone else has also found his channel.
I eagerly await more reviews of other USB-C PD chargers, e.g the 65W Lenovo ones you can get for pennies on ebay.
Does anyone review USB-C outlets? I want a high watt one, but I'm worried about whether they are truly UL listed and won't burn my place down
Seconds the recommendation of AllThingsOnePlace as great place to learn about usb psu in general. But watching his video I can't help but wonder with all the talk about the important of energy at the national level, why this kind of analysis is not done by one of gov. Agencies ...
> I can't help but wonder with all the talk about the important of energy at the national level, why this kind of analysis is not done by one of gov. Agencies ...
This kind of thing used to be more common in the US but in the 80s various trends, from ideological privatization to increased tolerance for "gaming the system" and an increase in regulatory capture, squeezed this kind of thing out. Not completely (car models get crash testing, for instance) but, for example, FDA no longer does its own prospective research, but responds to applications from the private sector (and when it has questions, has the requestor do the research).
I wonder if we'll start seeing devices other than laptops that currently use barrel jacks for power shift to USB-C. 240W covers the vast majority of things even an enthusiast might have on their desk.
It'd be nice if they did, if only because there's a single agreed upon way to deliver power with USB-PD, and USB-PD bricks hash out the details with the connected device to deliver appropriate power. It's a considerably nicer experience than with barrel jacks, with the various different sizes and pole configurations they can come in and their "dumb" nature all of which makes it easy to plug in a brick that physically fits but fries your device.
It'd also enable better modularity, making it easier to replace the bargain bin bricks that come with some devices with something higher quality.
It's already starting, I've noticed. I've gotten a few very random devices lately they would traditionally have been powered by a custom barrel jack, that are now USB-C instead. One was a cheap light up dog collar, and I've recently picked up a soldering iron with it.
I expect the trend to continue as it's likely cheaper to toss in a single USB-C port and controller chip than it is to supply a power brick. I can see most stuff shipping without an actual PSU very soon - I'd estimate 50% of devices already do so these days.
Part of it could be due to the EU legislating USB-C for charging on quite a few consumer products. Shipping a charger, let alone a proprietary charger, is rapidly starting to become a con rather than a pro.
And USB-C is starting to become dirt-cheap to implement on the device side. 500mA @ 5V can be done without any controller chip whatsoever, and you can do up to 3A @ 5V without active communication. It's just easier to use USB-C than it is to mess around with a custom power brick!
The big problem I’ve found is a lot of “cheap” things that have usb c don’t support PD. I have some hair clippers, a flashlight, some wireless ear buds and a semi expensive electric screw driver (from Lidl!) that have usb c but only charge with a usb a to c cables. It is infuriating.
That sounds like they skipped a resistor: https://hackaday.com/2023/01/04/all-about-usb-c-resistors-an...
Someone made a fix, but it requires soldering: https://github.com/ide/usb-c-to-c-power-mod
I've found connecting a usb-c to usb-a adaptor and then a usb-a to usb-c adaptor (effectively, c-to-c, but with two props) some times will trigger the traditional power deliver. Try on either end of the device.
The only two devices I have that still need it, a mouse and beard shaver, I use them irregularly enough (charge around once every few months) that this solution is good enough for me instead of having an extra plug+cable. Yes, it won't charge as fast as an actual usb-a to c cable, but for my case that's good enough.
Yeah, it's pretty infuriating, but it's still so much better than proprietary barrel jack crap
Already happening. My soldering iron, pimple-popper camera, and toy lightsaber all take USB-C. Though the lightsaber isn't compliant and just wired up the power and ground pins from the USB connector with no more complexity than barrel jack, rather than doing the proper USB-C/PD things to indicate how much power it can take, so some cables/chargers won't even give it anything.
>pimple-popper camera
Excuse me but, what?!
Specifically, this: https://www.amazon.com/gp/product/B09HTWH46C/ It's much easier than trying to hold a mirror with one hand so I can see what I'm doing with the other hand.
Holy cow, that's a more important invention for humanity than that Apple VR headset.
I'm afraid to google it because then my ads will be nothing but skin conditions for weeks.
Has been happening for the sub-60W market for a long time.
Lenovo has also gradually been adding USB-PD to their gaming laptops, first at 100W and by now I believe at 140W. Though the one I use can use up to 300W and the only viable aftermarket charger is the SlimQ 240W, which can do either 2x100W PD or a range of barrel plugs (and lenovos high-wattage rectangle) on one relatively small brick.
I had idea of making adapters that have barrel jack on one side and USB-C port on the other. The 5V ones would be easier but would need ones for different voltages, which would either need USB-PD PPS or transformer in the adapter. They would currently be expensive and only for people who really hate wall warts. The other problem is that multi-port USB-C chargers are rare and expensive.
My impression is that most devices with barrel ports don't use that much power and would be fine without USB-PD. They use barrel ports because they were designed before USB-C or because USB-C port is too expensive. I supsect many would be fine with USB-C to USB-A cable and charger.
You know what they say. There's no such thing as original thought.
https://www.adafruit.com/product/5450?gclid=CjwKCAjwm4ukBhAu...
I have a 180w gaming laptop, and would love even just having a GAN charger for it with a barrel Jack. But they’re hard to find at that wattage, never mind a usb-c one.
VoltMe make a 140W GAN charger, which I didn't try. Instead I replaced my Asus G14 (w/RTX3050) 180W brick with their 65W GAN USB-C PD charger and it provides ample power for regular non-gaming use. When momentarily going over 65W the battery is called to the rescue but it gets recharged quickly enough afterwards to maintain a comfortable margin. I very much appreciate the weight difference when travelling.
This is great to hear! I think I’ll do the same.
USB-PD requires extra circuitry that barrel jacks don't. I doubt we'll see the end of barrel jacks.
Technically yes, but not really. The only requirement is two $0.001 resistors on the CC lines, giving you 500mA @ 5V. You can get up to 3A @ 5V simply by measuring the voltage the charger puts on the CC lines, so that can be done in $0.05 in parts.
Getting the full 5A @ 20V experience is possible with a chip costing less than $0.50, so even that isn't too expensive.
Reference, please? Everything I see that does standalone UFP (upstream facing port) PD winds up costing a LOT more than that.
The Cypress/Infineon chip that does this is around $2 and requires quite a bit of external circuitry: https://www.digikey.com/en/products/detail/infineon-technolo...
OTOH, a lot of things have stopped including transformers, so the tradeoff might be worth it for the manufacturers.
Exactly, the dc-dc bricks should more than offset the USB C costs.
there's enough cheap parts floating around now that offer standalone conversion from USB-PD to raw DC voltage. if customers are preferring USB connections, OEMs will find a way to implement it.
something like this is no more difficult to implement than a barrel plug https://www.aliexpress.com/item/1005005315614647.html
I took a few of those USB-PD decoy boards and soldered them to some universal power jacks. Now I have a home kit that can power any legacy barrel-jack devices. I did have to label each cable with the hard-wired voltage so I don't mix them up.
Basically a DIY version of this: https://www.aliexpress.us/item/3256804001423573.html
maybe for the truly cheapest products, but USB-c PD chipset can be pretty cheap these days.
Barrel jacks already have extra circuitry in quite a few of them. Dell is notorious for this; if you use a non-Dell charger it won't even let you charge your laptop.
Is it possible for a (laptop + USB-C PD power charger) to support multiple charging rates?
My Lenovo Legion 5 has a 300W charger. Caveats: (a) I'm not sure if that's input power or output power; and (b) it's not a USB-C PD connector , but my question isn't specific to this laptop.
Airplane A/C power outlets aren't willing to deliver that much power. And even if I was willing to slow-charge the laptop on an airplane or with my car, the laptop isn't willing to cap the charge rate, so it's simply not an option.
So I'm wishing for some scheme that lets me slow-charge a laptop in those situations, even if it meant having two different A/C adapters.
Great ask. There's no reason devices couldn't negotiate lower power. With USB-PD, power sources offer Power Delivery Objects: different charge modes they can do. It's up to devices to pick.
Right now most devices pick the highest power option (that they can handle). For a variety of reasons, it would be super sweet if we could pick lower power options! Maybe it's a multi-device charger & you want to leave more capacity for other devices. Maybe you want to slow charge your battery to extend it's life.
Almost every usb-pd device can accept lower power options, if plugged into a charger which doesn't offer the maximum rate. The only thing missing today is software, is user control over the power delivery negotiation process. Very very achievable, with minimal effort.
Notably, depending on the device, it may not actually pick the highest option it could handle. It may automatically adjust the voltage over time (state of charge, usually, dictates this) to compensate.
There's also an optional usb-pd PPS (programmable power supply) where the device can ask for a specific voltage with 20mV granularity & adjust the ask on the fly. This let's devices just pass through power directly to battery while still letting them finely control charge curves. Neat stuff.
But even just adjusting between, I to make up an example, 15V while charging battery, down to 9V after charged, is quite possible. I forget specifics but I almost think I remember there being a minimum amperage draw, so devices canr just ask for 20V then just sip 0.01 amps... They are required to step down to lower voltages if they need so little power. I'm not sure about this though!
PD interposer device that can mask PDOs?
Yes!
I hadn't considered such a widget until your post, but now that you mention it I would totally buy one.
> Very very achievable, with minimal effort.
Not with how complicated the whole stack is...
We still can't say "don't charge if other device has no AC power" even tho that info can be propagated via USB-PD...
I genuinely don't think it's that complicated. There's a perception about that, but look at the wire protocol for a couple devices & it starts to feel extremely rote extremely quick.
There's a very old very extensive USB HID spec for a ton of battery & charger telemetry things, that for no good reason was never implemented. I'm not sure if USB-PD has overlapping way of sharing data like "is the other side also running on battery?" but we have had the technical possibility of answering that (and how much charge is left what the battery voltage is, but getting low power alarms, more) for literally decades & shame on us for never having implemented it.
> I genuinely don't think it's that complicated. There's a perception about that, but look at the wire protocol for a couple devices & it starts to feel extremely rote extremely quick.
USB-PD standard is 500+ pages. I remember some early adopters (before ready-made usb-pd controllers were available) complained about that, that the PD code was far bigger than rest of their gadget code. Hell, just look at amount of PD stuff that was subtly or not-so-subtly implemented wrong.
And it's like, they decided to invent their whole own PHY and wire protocol instead of just using CAN or one of the RSXXX ones, for no discernable gain.
Sure it is easier now but not because standard is, but because chip manufacturers made chips specifically to handle that mess...
Yes, this is what USB-C PD is for. If you have a laptop capable of charging at 100+ W but you plug it in to a 45W charger, it will charge at 45W and maybe give you a notification about slow charging. (Sometimes you'll run into weird exceptions where either the charger or laptop doesn't support a particular voltage or has a lower current limit for some voltages so charging power can end up lower than you'd expect.)
My Lenovo Thinkpad X1 has a specific setting that allows it to charge off a lower power that you can access through a setting in windows.
Yes, there exist many devices that support multiple charging rates. My phone allows the selection of 3 different wired charging speeds, as well as two different wireless charging speeds, selected in software.
Unfortunately, due to cost or incompetent engineering, most devices only accept either a few charging configurations, often just one.
I didn't realize this as my first laptop with USB-C ports could be charged with any USB charger, even a dumb 5v 500mA phone charger would eventually get the job done over a couple days. I just assumed everything was like this, but unfortunately not. A lot of laptops and cameras will refuse to draw any power at all unless they can negotiate certain configurations.
It's too expensive for a feature that most people don't think to look for.
Lenovo connectors does have resistor on center pin that indicates charger rating. So you could jerry-rig adapter cable that makes laptop think charger is lower power than it is (or just buy lower power Lenovo charger).
the nice thing about USB-PD is that you can connect any PD-compliant charger to any PD-compliant device, and get some charge.
so even without any software or clever switches to slow-charge your laptop, if you took a USB-PD laptop that prefers a 240W charger and plugged it into your 50W tablet charger or 20W phone charger, it would charge. it would just do it a lot more slowly than witht he high-power charger.
I suspect your lenovo works the same way - if you plugged it into a 65W thinkpad X1 charger, it'd probably slow-charge your laptop.
This is not a given, though: it has guaranteed forward compatibility, not backward compatibility.
Charging a laptop from a 20W phone charger usually doesn't work because the laptop will have a minimum voltage/current requirement, but charging a phone from a 240W laptop charger will always work.
That has been my experience as well. I've not come across a laptop that accepts a charge from a low power USB-C PD charger. I'm aware the standards allow for falling back to lower voltages but it seems laptop manufacturers specifically go out of their way to stop this. I presume to avoid issues with their battery charging system.
I have this laptop and I've charged it with USB-C PD at 90W on multiple occasions. What chargers have you tried?
Wouldn't airplane outlets just limit how much watts come out? I'm not an electrical engineer, I don't know much about these things, but I'd assume they have protection built-in to just cap out instead of blow a fuse if something draws too much power.
The trick with my Lenovo 300W notebook in the airplanes is as following.
At first, with the adapter disconnected from the notebook, I charge the capacitors inside of the adapter by connecting and re-connecting repeatedly (1-2 seconds intervals). The first 5 times the breaker trips, but eventually the capacitors are charged, so no initial high current is drawn from the socket, and the breaker is happy.
Only then I connect the notebook to the adapter. I never tried to draw too much power from the airplane socket by playing GPU/CPU intensive games.
Wish you productive flights!
Oh so this is how airplane sockets get that way.
That's not really how electricity works. Wall power is a stable supply. 120v going up & down in a sine wave.
If someone is drawing 120w - 1 amp - your only control as a power source is to try to lower the voltage (voltage potential). Problem one: that will go out of spec with what devices expect, if you try to provide 80 vac instead. Problem two: switch mode power supplies that can handle sagged voltages will just try to draw more amps to get the same net power.
There's really not a good way to "cap out" power. The device just sees voltage potential (volts) and doesn't know to go lower. Blowing a fuse is the only real indicator we have.
To be ultra pedantic, 120VAC refers to the root mean square (RMS) voltage of the sinusoidal waveform present in household electrical systems. The RMS value represents the effective voltage that produces the same amount of power as a DC voltage of the same value. In the case of a 120VAC circuit, the peak voltage, which represents the maximum value of the voltage waveform, is approximately 169.7 volts. This peak voltage is achieved when the voltage swings between +169.7V and -169.7V in a full sine wave pattern.
There is, just not for "AC wall voltage". It could simply drop the voltage and expect the other device to say start limiting current when it goes 5% or more below nominal voltage. Akin to how MPPT works on solar chargers
It "just" requires both sides to support that. Which won't happen as we already have USB-C if you want to negotiate the power usage.
We could invent other signaling strategies too. Maybe we lower the voltage by 5% as a "low" signal. Now we can yell at the device in binary, and more explicitly spell out the conditions.
Maybe the source sends S-O-S in Morse code. Maybe it sends a requested max power.
We can invent signalling strategies to communicate yes. EV chargers use HomePlug Green for example to commitcate. This could be consumerized & put into all devices, used to perform negotiations. https://en.m.wikipedia.org/wiki/HomePlug
If we wanted to go entirely analog just simple CV/CC on the power source side (meaning "keep constant voltage up till max amps, then start dropping voltage) + MPPT-like controller on the sink is enough. That's easy enough to be done on off-the shelf chips.
>We can invent signalling strategies to communicate yes. EV chargers use HomePlug Green for example to commitcate. This could be consumerized & put into all devices, used to perform negotiations. https://en.m.wikipedia.org/wiki/HomePlug
I'm kinda surprised that's relatively rare approach, in-band communication like that saves 2 wires so would technically allow USB-C to get extra 20% power boost over same connector. I think I saw it used in some solar stuff to coordinated various devices of same manufacturer.
Waste heat seems like it would be a thing? Even at 95% efficiency (which is unrealistic), we're looking at a 12W heater.
240W chargers were a thing even before that, for gaming laptops. The only difference here is that it goes through USB-C PD, instead of a large-ish barrel jack, right? 95% efficiency probably refers to the adapter itself, where it shouldn't matter that much. Additionally, GaN is now a thing, so efficiency should be better than what it was 10 years ago.
It says in the article:
>> The company says it uses Weltrend WT6676F, ON Semi NCP1622, and JoulWatt JW1556 controllers, as well as GaN switching parts from both GaN Systems and Navitas “peaking at an amazing 93% efficiency” for this 180W adapter. Both those parts and Chicony’s assistance as a power supply manufacturer are obviously there for other companies to use as well.
So likely even less efficiency for the higher rating. I'm very interested to see how they're venting this heat passively.
Should pipe it off to be a coffee cup heater.
The size of these kinds of high wattage passively cooled power adapters is dictated less by component density and more by what you can spread and dissipate through the enclosure with safe touch temperatures.
And with the new solid state cooling tech that is just now starting to be rolled out I imagine in a few years some power supplies will be actively cooled.
That doesn't mean you have any less heat to dissipate.
Apple's M1 in the MB Air is 10W TDP afaik. The PSU would be more constrained space-wise but it'd probably get somewhere about as hot as the passive cooled MBA at full load.
Is 12W meaningful heat? I mean, I have laptops that run 10-15W and it doesn't seem like much. I guess it feels hotter because it's a much smaller surface area, but not that much (laptop heat output is mostly over the CPU/mainboard anyways)
It doesn't get the chance to build up in a laptop because of the fan. A 20W phone fast charger gets much hotter than a laptop, even though they should only be wasting a couple of watts on heating, because they have no active cooling (and pretty poor passive cooling).
In a climate controlled office or cold climate? Probably not. In an area that has hotter climates or high humidity? It doesn't sound like a fun time.
Has always been the case, i remember my legs getting cooked by apple's magsafe charger brick. GaN makes this better now though
It seems Gallium Nitride are quite the revolution in power density for charging equipment
I now own two Anker GaN chargers. They're awesome. I carry this single little 70 watt brick, 1x usb-a 2x usb-c ports. Charges everything. Even my macbook pro, albeit at a slower rate.
Absolutely.
I think it's also super important that there is now a market of competing products too. Until recently, devices were sort of stuck using whatever the manufacturer provided. Almost no one shopped for power density. Now we have an interoperable standard & different companies can compete to be better.
USB-PD has been pretty epic so far, IMO.
It's been quite nice to have a 150 W charger in such a small form factor. Particularly since these charges tend to come with multiple ports in case you want to go from "I'm just charging my MacBook" to "I want to plug a couple of things in overnight at the hotel but don't want to pack a bunch of chargers". Typically that's some combination of my watch, airpods, phone, and laptop.
My current charger of choice is the Anker 747 150 W, 3 usb c (equal capabilities per port of 100 W) and 1 USB A (24 watts) but there have been a lot of other models released since then. Somewhere around ~240 W might be when I look at options again, right now my MacBook won't charge at full speed due to the 100 W limit on the 747.
GaN doesn't actually change the capabilities, just the size required.
Which is power density
The Hdplex 250W [1] is pretty small, seems like it proves it's possible at least.
1: https://hdplex.com/hdplex-fanless-250w-gan-aio-atx-psu.html
ATX power supplies are a much easier task. Fixed voltages for everything. A USB-PD charger capable of 240W is essentially a variable power supply from 5 to 48V. Much more difficult in execution.
Rather the opposite, actually. ATX power supplies have to supply -12V, -5V, 3.3V, 5V and 12V at the same time. A USB-PD charger only has to supply a single voltage.
And pretty much all power supplies are switched-mode power supplies anyways, whose controller usually requires you to explicitly define the output voltage using feedback components. Changing that to a variable power supply like USB PD doesn't really require much engineering.
On one side, I like the idea (and I use it a lot) with USB C to power a notebook. I have a small 65W travel adapter and I can charge my beefy HP Z-Book (it even works with a 45W adapter) or my smaller Fujitsu U939. But both notebooks still have real charging ports too and normaly I use those. A real charging port are much less fragile when moving the notebook while plugged in. USB C is very fragile and it is an very, very expensive port just to load a notebook. When you use it as docking station, then, yes it makes sense, but just for charging everyday, I still much prefer a normal charging plug.
> it is an very, very expensive port
Expensive in terms of cables or connectors?
In both cases, I've been paying considerably less for USB-C (cables and chargers combined) than for proprietary replacement chargers.
> it even works with a 45W adapter
My favorite thing about USB-C charging is that (at least Macbooks) it works even with lowly 5W chargers in a pinch! Sure, it takes more to fully charge a laptop that way – but I can sustain my Macbook Pro's charge with an 18W phone charger on an airplane no problem.
> ”USB C is very fragile”
Is it? I’ve been using USB-C Macs since 2017 and I’ve never had any broken ports, despite some significant abuses (cable trips, grime in the port, etc). A few worn out cables, and failed chargers, maybe… but no problems on the laptop itself.
On a clean table it might be not a problem, but if you work in an industrial environment or so, where the notebook maybe just is on a box or on the floor and next to heavy tools. Also if you move the notebook around while plugged in, I think with USB-C you really have to hold and support the cable.
> “if you move the notebook around while plugged in, I think with USB-C you really have to hold and support the cable.”
This was true on my 2017 MacBook Pro - the grip force was quite weak on the USB-C ports. But not so much on my M1 MacBook Air (2020), where the ports feel much tighter with more grip.
According to my technician friends, yes. Apparently on most devices, USB-C ports are much less robustly attached than USB-A and are more prone to failure. Just because it's fine on Macs doesn't mean it's fine everywhere else.
I haven't seen a failed port yet. I see loads of failed MicroUSB though.
On newer devices or devices that have been in use for over a decade? It's comparing apples and oranges, since USB-C is just now becoming ubiquitous. I've already seen a lot of issues around build quality and longevity (outside of Macs). It's one of the more common issues I see on forums with more recent laptops nowadays.
I beat up a 12" macbook (the ones with only one port, a USB-C port) for years, and never had a problem with the port.
USB c port modules on the 13 inch framework are I believe $9. And made to be easily swapped in and out.
Great! I'm going to need something like fpx or fabpide2 with a Lenovo connector and at least 135 watts so I can avoid buying more Lenovo charging bricks for the couch, bedroom, second desk, travelling...
I have this dream where Apple releases the most amazing self-driving, electric vehicle and it charges via Lightning cable.
It's super frustrating that if I want a 2nd charger for my macbook pro, I have to either buy an overpriced apple adapter, or.... what? I haven't seen any USB-C compatible 140W chargers that are significantly cheaper than apple's.... but I can't charge my laptop with less. If I plug in my 80w charger, my laptop just goes "bong bong bong" as it turns charging on and off endlessly.
This is a very weird way of saying the that Apple charger is priced competitively and isn’t over priced at all.
How much is a 140W charger supposed to cost? That's a nontrivial amount of power for something which needs to support multiple voltages: there needs to be thermal management and safety circuitry to match; it's not "just a bigger 5W charger". As another commenter mentioned, Anker's 140W charger is not much cheaper than Apple's.
Anker 717 is much smaller and is cheaper, though not by much. Considering it just seems strictly better, it doesn't need to be.
This really makes me think about use cases. Personally I want my laptop to be as light and portable as possible; some of these bricks are likely heavier than my whole laptop! When I need crunch I do it on a desktop or in the cloud (or these days "...and in the cloud"). So I edit code locally but when I press c-X c, g++ runs on some other machine.
I don't really understand why anyone would lug around an enormous and expensive boat anchor, but I'm sure they aren't idiots: they must get value from doing so, even if I can't imageine what it would be.
One thing I love about capitalism is that it's a huge parallel processing system for satisfying these different needs. If I were the central planning czar, the folks who needed the big portables would be SOL.
There is certainly a trend in processors as well as GPUs to push the hardware further by pumping more power into it. This (almost) always plays into the various workstation-grade laptops out there, which I suspect many won't unlock their full potential without a beefy power source.
Beyond gaming, the most interesting use cases I have seen and heard are CAD work/displays of highly complex models, creating heavy duty multimedia presentations, game development, and just about anyone in a country that either needs to do a lot of travel or does not have ready access to a high bandwidth connection. I don't know how prevalent those cases are, but they did surprise me a little.
The CAD case was my default guess, though I've seen from my ME colleagues that when you're designing something very complex you absolutely need the oomph of a real workstation class machine. I guess there could be a large "middle" of quite complex but not extremely so.
But how many people need that? I was shocked to see another colleague doing CFD on his ipad.
why was 240W picked as the upper limit for PD? Why does there even need to be an upper limit?
The usb-c connector is rated to 5 Amps (A). Usb-c went up to 20V already. 5A * 20V = 100W (where we are).
We didn't want to change the connector. So we are stuck at 5A. But we can raise voltage & still have some margin. So voltage was raised to 48V. 5A * 48V = 240W.
As for raising the voltage more, it's likely very technically feasible, but probably not, for safety reasons. There are various levels of what is considered safe voltages. Higher voltages have higher ability to injure humans, to cause shock or potentially spark. Voltage is a unit of electrical potential, essentially how bad some juice is desperate to get out. 50V is the "Safe Extra Low Voltage" (SELV) limit for AC. It's actually 120V for DC but 48V/50V has a certain dislodgable-for-now mindshare. https://en.wikipedia.org/wiki/Extra-low_voltage
Connectors also have limits to their voltage isolation. If you have 1000V that electric potential really wants to get out & will arc across gaps. If there's debris or a worn connector, the threat of say 200V causing some short is much higher.
We probably could go higher. Usb-pd is super safe. When plugged in, it's in a very limited 5V state. This is a high risk moment in the connection life cycle, as pins are sliding into place, but partially connected & likely not aligned fully yet; not having any real voltage applied at this phase is a colossal design win against so so so many power delivery mechanisms in the world. Device & source _after being connected_ then have to negotiate power, on the secured connection. They ongoingly perform bounds checking to make sure the power is flowing in an expected way & will disconnect if out of spec. The connector has good isolation. 120v * 5a would be 600W and is still SELV. Add some thermal protection to the ports to make sure everything's OK there and it's probably going to just work. But any mishaps (ex: puncturing the cable, debris inside the device causing a short) would be more severe/scary. I'd love for some hackers to find out how high our connectors can go. Maybe in lab conditions we can get a usb-c connector doing a couple hundred volts fine. I would be unsurprised. Being safe for the real world though, after wear, and what happens when there is a fault is why we have SELV. But again, SELV says we could go up to 600W on this connector maybe.
One non-concern should be any additional heat, such as on cables & connectors. Since amps are still only 5A, the power loss is actually the same. Pretty great.
> When plugged in, it's in a very limited 5V state.
Depending on what's on the other end, it's actually even better than that would imply most of the time.
If both sides of the cable are in spec-compliant USB-C ports, then the power pins will be left at 0v for the initial connection, and only the CC pins will have a minuscule amount of power coming from the source (charger) - just enough to detect specific levels of resistance on the sink (phone/laptop/etc.) for 5v power and/or negotiate a higher voltage for USB PD.
Once they've established that one side is a source and the other side is a sink, then the source will provide power on the power pins of the cable.
If a USB-C cable is used to connect one charger to another, for example, then the negotiation will fail and neither charger will provide power on the main power pins.
USB-A ports, on the other hand, always provide 5v, so USB-A to USB-C cables always provide 5v on the main power pins.
The reason some cheep chineese electronics with USB-C connectors can only charge with USB-A to USB-C cables, not with USB-C to USB-C cables, is that they skipped the CC pins entirely. I actually modded one device by adding in two half-cent resistors to make it able to charge from a USB-C port: https://www.nfriedly.com/techblog/2021-10-10-v90-usb-c/
> The reason some cheep chineese electronics with USB-C connectors can only charge with USB-A to USB-C cables, not with USB-C to USB-C cables is that they skipped the CC pins entirely.
If anyone has a usb-c pass through adapter that can negotiate for 5v out, please please please share. Ideally for me it'd be a like 3 inch cable that that a male & female connector.
Extra credit if it uses usb-pd to try to ask for 5v 5a.
(these would be incredibly out of spec & could cause damage to systems, but mercy they'd be useful! I find this problem to happen on a bunch of devices, alas not just cheap/rare ones)
You can plug an A male to C male cable into an A female to C male cable, that gets you a (directional) C-C cable with guaranteed 5V output.
I'm so close to having zero usb-a in my everyday carry. But this is still a good suggestion & I often can do this already.
Negotiating voltage after being connected avoids the problem of sparking while the connector is being plugged in, but I don't think it helps with avoiding sparking in the process of unplugging the connector? Unless one of the leads is shorter so that is disconnects first and the circuitry can detect that and turn off the power super fast?
You are absolutely correct, and the USB-C specification even has an entire appendix dedicated to the problem. The trick is to reduce the voltage difference until the plug is far enough that a spark is no longer an issue, which means placing an appropriately large capacitor at the Sink side.
It’s designed around 48V and 5A. Higher voltages introduce additional risks around arcing and also get you into different safety regulations and requirements. Above 5A also starts to make cable and connector design difficult for a small connector like USB-C.
Last time I looked at the comms protocol, it seemed possible to request up to 10 amps. I'm not sure there's a physical spec for a matching cable, but there's also no way for a cable to communicate its current limitations.
> there's also no way for a cable to communicate its current limitations
I don't think that's quite right. USB-C cables that support >60W (>3A @ 20V) must have an e-mark, which is a small chip embedded in the cable that identifies it as being able to support specific levels of power, such as 5A @ 20V for 100W or 5A @ 48V for 240W.
Spec-compliant chargers won't supply more than 60W unless the cable has the appropriate e-mark.
Good to know, thanks! I was interested in the comms side and not the cable side since I was considering building a widget that didn't use USB-C as the physical layer but did use PD for power negotiation.
Nothing prevents anyone to use the USB-PD protocol over a different cable and plug (and maybe some do but we don't know it) rated for 10A. It's just so much more practical both for users and when designing to just use off the shelf USB-C (which AIUI has its design rated for 5A) as the physical part.
Thanks! That's exactly why I was looking into the comms side but didn't spend more than a couple moments on the cable side. I was considering building something that had board-to-board connected modules and used PD to negotiate the power between boards.
USB-C cables other than basic low speed 3A ones are required to have an embedded e-marker chip that enumerate the capabilities of the cable.
I'd assume it's not specified as a upper limit but that it's just the highest voltage/current-pair currently defined.
On a more fundamental level, there's the physics of how much power you can pass through a cable/connector safely.
This made me curious if it would ever be possible to see some material more conductive than copper in consumer cables.
Doing a quick bit of research there isn’t really any other option. Silver has 7% less resistivity than copper, but it tarnishes.
Aside from that, humanity hasnt discovered other options!
...ohm's law ? P = U * I. Yall skipped high school physics or something?
USB cables can only get so thick. And voltages only can get so high to not be dangerous to people.
It's not really the thickness of the cable, is it? The constrained part, that has to stay the same regardless of what cable you buy, is the thickness of the pins on the connector. Where, presumably, any resistive heat from that connection is dumped into the body of the device being charged (just like resistive heat from operating a 1600W space heater with a big, thick extension cable gets dumped into your the electrical box behind the socket it's plugged into.)
The pins go very short way so even if the resistance of them is far higher than a cable they are pretty short to dissipate any significant power. At least from my experience in sketchy connections. But yeah, definitely another limit here
Voltage too, at some point it would just be too close for the voltage and would start arcing.
5 amps is the highest current official USB cables will carry, and 48V is the highest voltage you can generally use as anything more is not considered intrinsically safe to handle -- it's the maximum "low voltage"
Thus you get 5A @ 48V which is 240W.
I know that increasing voltage at those minuscule distances that usb-c opeates can cause electric arcs which is dangerous
Increasing current on the other hand heats stuff up which... is also dangerous
USB-C solves the arcing problem in a similar way that CCS (EV chargers) does. It doesn't engage the high voltage pins until a low voltage pilot makes contact.
I'm not sure exactly how USB solves that for disconnecting (CCS locks the connector in) but I imagine the pilot would disconnect first and that would kill the PD pins during disconnect.
It seems that 48 volt USB-C might still have some issues with sparking during disconnect.
There's likely a better source but here's some discussion on the topic I found.
https://www.reddit.com/r/UsbCHardware/comments/106d7vi/usbc_...
> but I imagine the pilot would disconnect first and that would kill the PD pins during disconnect.
Don't imagine, just look at USB-C socket. So the answer is "not really", at least I didn't noticed pins for the power being longer
The 240W cables have a different spec so that's not indicative of what you'll see for 48v.
Just watch: in the future we will have step up transformers instead of step down transformers so the charging cables can be thin again and charge fast
I might be misunderstanding, but charge pumps are already a thing: https://en.wikipedia.org/wiki/Charge_pump
Obviously there's stepping up and down happening on both ends up this cable (since it's probably a 19V lithium ion battery in the computer), but at the end of the day you still need to decide on a safe and practical volts*amps number, and then spec the cables and connectors accordingly.
That's pretty much already the case when using power banks!
Because you have to size the cables based on amperage. The highest voltage supported by USB-PD is 20V. At 20V to deliver 240W you need 12 amps. That's already a fairly high number. At 300W you'd need 15 amps.
So unless you want to drag around an NEC type cable as thick as one of your fingers, you need to set a limit.
Edit: Fixed math. I haven't had caffeine yet.
That was my first question -- is this still going to be at 20V? The kind of current that would draw is crazy for those tiny pins.
Looks like the spec goes up to 48v now:
https://en.wikipedia.org/wiki/USB_hardware#USB_Power_Deliver...
It's 48V.
While amperage is indeed a problem, PD 3.1 uses 48 volts to deliver 240W. https://www.usb.org/usb-charger-pd
That’s only 5 amps, but such a high-ish voltage is enough to lead to arcing. Charging cables are likely to require additional safety measures.
Not even safety requirements, going above 48V will start subjecting to your device to electrical code.
USB-PD now supports 28, 36V & 48V as well because of the higher wattage limit[0] (240/48=5A which is about what the cables are rated for I believe)
The 240W profile uses 48V
I'm glad we're finding faster and faster way to consume the earth's resources.