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USB Power Delivery: Plugging into the Benefits

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Re: USB Power Delivery: Plugging into the Benefits

#51

Post by JMiao »

edent wrote: post #2

I've basically stopped buying any portable electronics unless they take USB-C. 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 decen…

we are talking about a lightweight charging cable. you can carry more than one. boom, redundancy. being ideological about a cable connector is the nerdy equivalent of jony ive obsessing over macbook thinness.

Re: USB Power Delivery: Plugging into the Benefits

#52

Post by seba_dos1 »

edent wrote: post #2

I've basically stopped buying any portable electronics unless they take USB-C. 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 decen…

> 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.

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.

Re: USB Power Delivery: Plugging into the Benefits

#53

Post by seba_dos1 »

megous wrote: post #19
myself248 wrote: post #5

Earlier quoted context omitted.

The thing is, making a 5v-only device PD-compliant is literally one resistor. It costs well under a penny. 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 th…

Only if the device's consumption is < 2.5W, which is what a USB 2.0 computer USB-A's data port limit is. Anything above that, compliance gets a bit more involved and complicated.

Yes, but that's the case with microUSB as well. In fact, refusing to work with underpowered source is easier with USB-C.

Re: USB Power Delivery: Plugging into the Benefits

#54

Post by seba_dos1 »

mschuster91 wrote: post #42
exmadscientist wrote: post #26

Earlier quoted context omitted.

That's how it's supposed to work, yeah. 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.

> 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…

They mean bad USB-A to C cables with no resistor on CC line. Of course this is broken junk which will work with some devices and won't with others. I've also seen cables with resistors on both CC lines, which is also broken but in a slightly subtler way.

Re: USB Power Delivery: Plugging into the Benefits

#55

Post by ranger207 »

hazkoulia wrote: post #4

I'm looking forward to USB-C PD small format factor PC's. A decent amount of room in the PC cases is taken up by the power supply. And if USB-C could somehow provide a range of voltages to the motherboard, SFFPC's could be downsized even more

I have a couple like that in my mini rack. The problem is the power supply: these take 65W, so I figured I could get a quality 140W charger and power them both, but it turns out that things like "unplugging something else" would kill their power. I had to spend a lot more on a StarTech charger to get the performance I needed

Re: USB Power Delivery: Plugging into the Benefits

#56

Post by SchemaLoad »

seba_dos1 wrote: post #52
edent wrote: post #2

I've basically stopped buying any portable electronics unless they take USB-C. 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 decen…

> 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. 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,…

I think what they mean is not PD related at all, but the fact some cheap junk has a broken USB-C setup where it's missing the resistor that signals a device has been plugged in and to turn on the 5v power. While USB-A just have 5v live at all times.

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.

Re: USB Power Delivery: Plugging into the Benefits

#57

Post by seba_dos1 »

itnerd wrote: post #50

Does PD include a specification that allows a client device to share its current battery level? How does Apriv know which device “needs” a high output level? > 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.

Yes, since PD 3.1 (see "Get_Battery_Status" request).

Re: USB Power Delivery: Plugging into the Benefits

#58

Post by seba_dos1 »

exmadscientist wrote: post #13
hazkoulia wrote: post #4

I'm looking forward to USB-C PD small format factor PC's. A decent amount of room in the PC cases is taken up by the power supply. And if USB-C could somehow provide a range of voltages to the motherboard, SFFPC's could be downsized even more

> And if USB-C could somehow provide a range of voltages to the motherboard, SFFPC's could be downsized even more 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. Ge…

I quite like PD 2.0 when ignoring the legacy USB-A stuff. It's semi-elegant. 3.0 and further made it an abomination though.

Re: USB Power Delivery: Plugging into the Benefits

#59

Post by SchemaLoad »

miladyincontrol wrote: post #14
smallmancontrov wrote: post #12

Speaking of which, does anyone know a line of PD Decoy modules to convert barrel jacks to USB-C without the atrocious behavior of "oh, the charger doesn't have 12V, here's 9V have fun!" that the early ones all did? Ideally I'd like a little red light to come on or something, but I'd settle for not silently browning out the device.

iirc theres ones that do. However I dont recall there being any clean fix to the amperage constraint issues. Especially when a lot of usb-c chargers will vary output as they heat up with usage. 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 c…

You ideally want to get a USB-C brick that's over specced and from a reputable brand. Like if you get a macbook 140w usb-c brick it will work fine with everything.

Even for actual PSUs it's always been the advice that you want a decent amount of headroom to avoid issues.

Re: USB Power Delivery: Plugging into the Benefits

#60

Post by tredre3 »

JMiao wrote: post #51
edent wrote: post #2

I've basically stopped buying any portable electronics unless they take USB-C. 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 decen…

we are talking about a lightweight charging cable. you can carry more than one. boom, redundancy. being ideological about a cable connector is the nerdy equivalent of jony ive obsessing over macbook thinness.

Assuming your comment is only about proprietary cables that have usb a/c on the charger side, I tend to agree. Sometimes the device's form factor or function simply cannot accommodate usb-c without trade-offs.

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.

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