USB Power Delivery: Plugging into the Benefits
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Currently travelling with a laptop, watch, toothbrush, eReader, camera, bug-bite treater, and phone - all charging from the same power brick.
I'm guaranteed of getting a replacement cable / charger wherever I am in the world if I need it.
The only slight snag is some cheaper itema refuse to use PD and insist on plain 5V/2A - buy most decent travel chargers have NON-PD ports.
Amusingly, most of the buses I've taken recently also have USB-C ports on them for ad hoc charging. Perhaps one day EVs will use USB-PD-Max rather than CCS :-)
I've also returned a few USB devices that ship with a USB-A to USB-C cable and ONLY charge in that mode, they also MUST charge with USB-C PD.
The two so far were a therapy light and some Zippo hand warmers. Like, who in the hell would design a device that has a USB-C port on it where only a fraction of chargers will work on it. It feels even worse than proprietary charges, because you see a USB-C port on it and think, oh I have a plug that fits it, and then it doesn't F**ing work. Idiot engineering/product teams, making the world suck with their falsely advertised USB-C ports. If anyone of you are on a team that ever makes this decision, just know that it is a stupid decision, and jump ship when you can.
It's pure ignorance, not a decision, but the lack of one. Lack of caring, lack of having an actual engineer involved, just slapping an oval-shaped port into a product where a trapezoidal port had been, and blindly thinking that magically makes it spec-compliant.
Or not thinking about the spec at all.
I return these devices too. Lots of them. My e-commerce returns over the last year are probably 50% PD non-compliance, 50% all other defects combined.
So... yeah.
The bigger issue is not really the parts cost, it's the fact that it adds an extra part to the design that has to be purchased and tracked and assembled and blah blah blah. This is the real reason it often gets left off on the bottom-of-the-barrel products. Many times there is no other use for a 5.1kΩ resistor. And it might not even fit well at the cheap sizes (0603 or 0402), and going down to 0201-capable assembly factory flow just for these two resistors is not going to happen.
5.1k is a surprising resistor value, a lot of modern designs don't really have anything else in that area. I'm often not able to combine anything with it when I'm cost reducing. 4.7k, sure, but there aren't a lot of those either... 2.2k is just not close enough a lot of the time (or ends up as 1k), and same for 10k. So, sadly, it often does stand alone.
I wonder if PD will cause a comeback of that value as more and more legacy device refreshes move to USB-C plugs.
5.1k is about the middle of the generic "some kind of pullup" range of 1k-10k, so it's a perfectly fine option for strapping resistors or for a non-critical I2C bus.
4.7k would of course have been better because it's an E6 value (+-20 via the spec) rather than E24, but it's still a value I would expect any PCBA house to have in stock at all times.
But I agree, 1k or 10k would be the obvious no-brainer. I reckon there's probably a technical reason for it, as it does act as a voltage divider together with the Sink pullup, so perhaps there are some restrictions there with the multiple values it needs to distinguish.
Usually 5k is a little too weak for I²C. Rule of thumb is that you want to be around 1mA, so for a 3.3V system you start at 3.3k. Generally 1.8k to 3.3k ends up being a pretty common range. More current is usually better than less current, so even at 5V where 4.7k might be OK (if you're even at 5V Vdd these days), going stronger is often a good idea. If power savings is a concern, or if timing's somehow important (did you find another touchy badly behaved I²C device? say it isn't so!) then it might be time to break out the active pullup structures (mostly current source type things). Once this is done and tested it tends to get fossilized, for good reason, so this one won't usually get swept up in a standard-effort cost reduction pass.
If you're just a microUSB device, you'll also check based on BC1.2. And you can ignore CC/Rp check. It's actually simpler.
I guess you can assume anything advertising itself as USB default is underpowered, but then you'd be wrong.
> but then you'd be wrong
Not at all, it would just miss signaling it's not compatible with, just like with all sorts of proprietary signaling protocols out there. The point is that with microUSB you have no other way, you have to implement BC1.2 (or some proprietary spec) which is often more complex than a comparator on CC line.
For proper detection of actually underpowered source without awful lot of false negative results, you always need BC1.2. You're just adding type-c CC pins circuitry on top maybe to detect what power is availabe in non-default-usb-power scenarios. If you just use CC pins for detection, a lot of your users will not like you, and will not understand why they can't charge your type-c port featuring smartphone or whatever with a perfectly capable 2.1A/5V charger connected via USB A-C cable.
Been there done that.
Supporting BC1.2 in a smartphone won't make it any more complex than it already is (been there done that). We're talking about simple equipment here, where handling USB-C power correctly can be easily done without any ICs.
The contacts are in the connector, you just need to bring them out and get the resistor on them, which is frankly a pain I shouldn't have to endure when USB-C has been out for 12 years. None of this is rocket science, the manufacturers just aren't feeling the pain.
Sounds like the juice may not be worth the squeeze on a USB-C refresh if I have to use an A-to-C cable for it anyway
By "that mode", do you mean "1.5A @ 5V" permitted by BC, or do you mean "3A @ 20V" permitted by non-type-C PD?
> Like, who in the hell would design a device that has a USB-C port on it where only a fraction of chargers will work on it.
Who in the hell would design a charger that can do Type-C PD but can't do either pre-Type-C PD or BC? Does the charger in question also shit the bed when a USB 1.0 device attempts to draw 100mA @ 5V? I hope not! Were it me, I'd return that crappy thing for a refund.
Neither - OP means devices with missing CC resistors which will fail to charge with a compliant PD source. (The A-to-C cable works because it provides 5V Vbus unconditionally.)
So if you are having complete charge failures, try a different cable.
But there is some trash out there in the world. A lot of it, actually.
Some naughty cables work with some naughty chargers work with some naughty devices. Postel's Law in action, I guess?
Usually the best place to fix it is by getting rid of the bad cables. Usually.
No. There is no USB-C to C cable that will charge a badly implemented device with a standards compliant charger. That is the entire point.
An USB A to C cable is completely standards-compliant and safe, even if it always supplies 5V on the C end - any standards compliant USB-C device should not activate the MOSFET on its Vbus line unless it successfully negotiates via CC.
A lot of devices are not actually standards-compliant. Some are close. (This may actually be worse.)
My experience has been that if the source and sink are broken, they are often hilariously badly broken and it is pretty easy to figure out that they are the problem, if not quite exactly what they've done wrong. But if things are flaky and weird and don't really make sense, it's probably the cable. Try a known-really-seriously-actually-standards-compliantly-good cable and many problems go away, even if the source and sink aren't perfect.
(Many sources and sinks aren't standards-compliant because, even though they easily could be, they're trying to work around the other end not being standards-compliant itself, because that's what you've got to do to sell a product. So they're close but not quite there. This is not always ideal.)
And no, such cables would still work in plenty of cases. You usually get them by having them bundled with devices they do work well with. In fact, they always work fine with the kind of devices you mention. These cables aren't as common as USB-C-shaped junk that's missing resistors on the receptacle, but I stumbled upon them anyway and I didn't really try to.
"A USB 2.0 only Sink that doesn’t support accessories and is self-powered or requires only default power and does not support USB PD may transition directly to Attached.SNK when V BUS is detected."
or 4.5.2.2.5:
"A port that entered this state directly from Unattached.SNK due to detecting V BUS shall not determine orientation or availability of higher than Default USB Power and shall not use USB PD."
or 4.5.2.2.11.2:
"The port shall transition to Attached.SNK after tCCDebounce if or when V BUS is detected."
CC detection, let alone PD negotiation is not needed. You can draw up to 2.5W right away from Vbus and be standard compliant without wiring anything to CC signals.
Of course if you try this with a DRP device like a smartphone, you'll get no power. But that's not really an issue for type-c chargers or USB A-C cable assemblies.
For just-getting-power from a USB A port into a USB C peripheral: There are supposed to be 2 resistors in the peripheral device [always], and also 1 resistor within the cable for USB-to-legacy cables[1]. That's 3 resistors, total, to get a relatively dumb USB-C equipped peripheral device to reliably charge from both USB A and USB C hosts/chargers/whatevers:
The cable itself: It gets an internal 56k pullup resistor between Vbus and USB C pin A5 -- which is the CC line [yes singular]). This resistor signifies the capabilities of the host/charger/whatever for devices that care (some do care, some do not care).
The peripheral: This minimally needs two pulldown resistors [commonly 5.1k], between each of CC1 and CC2 [yes a plurality] and ground[2]. This tells a compliant USB C host/charger/whatever "It's OK! Send the juice juice!" regardless of connector orientation.
[1]: https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%... section 3.5
[bleh]: Again, it is a confusing thing. Nobody said that dealing with such flexible, ambidextrous connections would be simple. CC performs a lot of different tasks: It can be a bidirectional serial bus for active PD negotiations, and/or a resistor network for passively dealing with power, and it's the bit that performs detection of cable orientation for applications where that matters, and it probably does other stuff too.
That single little wire is clever AF. It'd be simpler to use multiple wires instead of just one, but that would take more copper. Copper is expensive, and we each save a tiny bit of money (or a large pile of money globally) by using less copper instead of more of it.
So unless your cable is known-good, if you are having trouble, trying a different cable should be the first thing you do. It really does often get things working.
Contrarily, if you have identified a naughty cable, it should be immediately widlarized.
Except the old ways were weird in unseen ways, too. Some combinations of cable, phone, and charger worked well and some barely worked at all.
We're in much better shape with USB C and PD. It's generally a good, forward-looking way of doing all kinds of things.
I just wish the cables and ports were better-marked, and that manufacturers stopped fucking around by making non-compliant stuff, and that there were a clear way with two battery-equipped USB C devices to unequivocally declare that a particular one will charge the other (and not the other way 'round).
And yes: The non-compliant widgets should ideally be named, shamed, and Widlarized -- not simply tolerated or worked around.
USB-A has no ability to provide voltages other than 5V, so there's no need for indicating it's the max.
Not all chargers have USB-A ports. Many laptops don't have USB-A ports, so if you want to charge a noncompliant device from a laptop it won't work. Or a laptop charger, which is dedicated USB-C.
No need for a magnetic dongle. I literally shove a USB-C cable in there, charge for a couple of hours, then get a week+ of use. Does step count, notifactions, calls, etc.
There's more to the world than Apple and Android watches.
Lots of people assume that USB-C always uses USB-PD, but the basic signalling is done with resistors. Lots of devices only need 15W, and it is better than USB-A charging. If you want faster charging, buy more powerful chargers.
It has helped out in a bunch of unexpected situations (usually someone else's device)
I also have assorted products that won't charge c-to-c (some from respectable manufacturers even, like Philips), but I see you can get little adapters with 5.1K resistor you plug into said crappy devices to cover that, I will have to try some out.
I did lose my shaver's cable whilst travelling once, so I had to go to the barber to look presentable before a meeting. Not a big deal, but it goes to show that it happens. Had it been USB of any description, I could have bought one anywhere.
But then again I could have just as easily lost/broken the device itself and be in the same situation, so shrugs.
The thing, it's not just about what cables you have at home, or even which ones you bring on a trip. It means if you go out on a trip with a small bag and a battery, you only ever really need one cable. It means you don't have to think about "which cables do I bring?", completely removing a question. That's really nice!
Forget that noise. Now its all one cable. Laptop, game console, phone, wireless headphones, reading device, even things like flashlights and lanterns. All one cable, can all work with the same extra battery packs and the same power cords.
Every PD port will handle non-PD USB-C consumers correctly, so not sure why would you care about non-PD ports. There is no "plain 5V/2A" in USB-C though, it's either plain USB (100/150/500/900mA depending on enumeration state), 1.5A or 3A. If you want to advertise exactly 5V/2A, you need PD.
If you use a USB-A to C cable the device works because it results in a USB-C cable with an always active 5V.
I've been pleasantly surprised recently when I plugged in my OnePlus into the bus in a medium/small Belgian city and saw the supervooc animation. (And it was actually fast charging, a 8 minute ride gave about 15% battery.)
For anyone wondering about technical details, PPS chargers now show up as supervooc apparently.
> Using dual-port modules, the system recognizes that, say, one smartphone battery in the vehicle is at 5 percent of capacity and a second phone is at 75 percent. The programming module gives the former device 100W and the latter 25W.
Here's an example capture of an exchange between my MacBook Pro and iPad: https://imgur.com/a/8rZlN9X
The iPad responds to Get_Battery_Cap with Battery_Capabilities, which reports the total capacity in Wh:
USB Vendor ID: 0x05AC Product ID: 0x0000 Design capacity: 280 Last full-charge capacity: 280 Battery reference: valid
And then when the MBP asks for battery status, the iPad returns a Battery_Status message:
Battery is present. Present capacity: 14.2Wh Charging state: charging.
Later on, as the charging continues, the iPad will issue an Alert message:
Reported alerts: Battery status changed. Affected batteries: Fixed battery slots: 1
And then the MBP will send a Get_Battery_Status again, and so on. (Example capture here: https://imgur.com/a/TI5maV0
What's really cool is that this exchange happens both ways—the iPad also sends a Get_Battery_Cap message to the MBP, because it is also capable of acting as a source, and, if the laptop's battery drops sufficiently low, the source/sink roles may swap (using a DR_Swap message) so that the iPad ends up charging the MBP!
Lenovo have some,but sometimes require adapter cards. And a few of the Chinese N150 units will take PD power
It's great for hot swapping and more portable than a laptop.
You reeeeeeally don't want to do that. Cable inductance is a big deal, among other issues. You want the main DC-DC regulators on the board, usually right at the load, for the main loads. Most of the PSU bulk is for dealing with mains itself: handling 50/60Hz or mains isolation is just physically large. Getting in secondary 20V DC (or so) from a single connector and then regulating it down on board is pretty much the ideal solution.
(I can't even begin to comprehend the horrors of a USB-PD negotiation involving multiple voltages. It's already the worst standard I've ever had to deal with.* Don't make it worse!)
(* Not hyperbole, it is truly, truly awful. At least things like 60601 are bad because, you know, they're covering lots of stuff like lifesaving medical devices. USB-PD is... holy hell, it is just bad.)
Yeah but usually you don't have to deal with that yourself but have some sort of chipset that handles all the USB-C PD and, optionally, even data-lane muxing stuff.
Literally nothing inside it uses that voltage, so it'll just get downconverted to the single-digit voltages the chips actually need.
It wants to supply the maximum power possible as you don't want a device which can charge faster stuck at a lower rate, so it wants to renegotiate with the sink, and the lazy way to do that is a full reset.
I've considered just getting a bunch of 65W USB-C buck converters and DIY one.
Which is kinda part the issue, usb-c charging bricks, they aren't usb-c power supplies, there is no expectation of sustained output capacity. Thankfully at least some the multiport ones have renegotiation more or less solved cleanly rather than what is essentially rebooting the PD controller.
Even for actual PSUs it's always been the advice that you want a decent amount of headroom to avoid issues.
I don't think I've ever seen one of those type of converters output anything but 5V upon negotiation failure. Which one did you use that did that? Their logic being "pick the closest available voltage" I presume?
On the plus side some of the bottom tier anker chargers will do 12v.
Plus I think the very new PPS ones should too
You could always request a non optional feature and convert it up/down yourself
I bet that cable gets plenty hot at 200+ watts.
Those regulations go even higher.
I doubt they'll ever increase the voltage beyond the current 48V (I was actually shocked that they didn't stop at 24V) so toasters are forever away. But not an order of magnitude away!
There are things that shouldn't be powered by USB-C. But there are plenty of sub 100W consumer electronics devices that really should be USB-C. I waited years before Panasonic released their lamdash shavers using USB-C.
This is a non issue, IMO. Does it depend on the electronics being designed correctly? Sure, but that’s the case for all electronics, and most devices probably build on some widely-available standardized control boards from 3rd parties.
As a user, I’m sooo happy that I can bring a portable battery and a wall charger, and both can recharge every single one of my portable devices. From gaming handhelds to large, powerful laptops, to wireless earbuds, to cameras, to smart watches, to flashlights. All with very different power requirements.
Case in point, IKEA will happily sell you a very well built 20W power supply that provides 5, 9, 12, or 15V for less than $5 here in Canada, and you can get a similar price from legitimate Asian distributors, even when buying in limited quantities. If you're working on a small-batch electronic product, that's a boon to your BOM; if you had to go out and source a dedicated barrel-jack PSU with the same capabilities, it'd cost much more, and you don't know what kind of quality you'd be getting.
Where the standard really falls on its face, IMO, is in its opacity. You can get a chip that does the PD negotiation for pennies, but there is no way to inspect the protocol without shelling out thousands for a dedicated analyzer, so when things don't work, it's really hard to troubleshoot the reason.
(Disclaimer: I'm working on an open-source protocol analyzer, so this probably colours my view on the matter a little.)
for laptops, a bad-actor usb-c cable/charger can do so much more, unless your laptop has AI that can distinguish "is this signal really coming from monitor/keyboard/etc ?" I'd rather have plain-old DC adapters (or usbc to dc)
"The STM32G071B-DISCO Discovery board is a demonstration and development platform for the STMicroelectronics Arm® Cortex®-M0+ core-based STM32G071RB microcontroller and particularly the USB Type-C™ and Power Delivery controllers.
...
The STM32G071B-DISCO Discovery board discovers and displays USB Type-C™ port capabilities such as data role, power role, VBUS and IBUS monitoring. ..."
https://www.st.com/resource/en/user_manual/dm00496511-stm32g...
Around ~$70 US now. Was around $50 when I bought mine a couple of years ago.
STM32G071B-DISCO at Mouser or Digikey.