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USB Power Delivery: Plugging into the Benefits

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Re: USB Power Delivery: Plugging into the Benefits

#71

Post by crote »

SchemaLoad wrote: post #61
dotancohen wrote: post #29

Earlier quoted context omitted.

The issue is that a USB charger is not a USB power supply. A charger does its best, but makes no guarantee of constant power delivery or duty cycle. The power supply absolutely must provide its rated output at 100% duty cycle.

There's also the fact that devices would still need an internal PSU to convert the 28v USB-C to the multiple voltages that all the parts inside need. It would be smaller without the AC to DC conversion though.

This is already the case today. Those mini pcs often take 19V, so it can use cheap and abundant laptop PSUs, which use that voltage for battery chemistry reasons.

Literally nothing inside it uses that voltage, so it'll just get downconverted to the single-digit voltages the chips actually need.

Re: USB Power Delivery: Plugging into the Benefits

#72

Post by XorNot »

codethief wrote: post #41
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…

What toothbrush do you have? I've been looking for a USB-C charger for mine (standard Oral-B toothbrush) but the only ones I've found were from no-name Chinese brands and didn't work at all.

I bought this one and it works: https://www.amazon.com.au/gp/aw/d/B0BS1VXS6L?psc=1

Re: USB Power Delivery: Plugging into the Benefits

#73

Post by crote »

ranger207 wrote: post #55
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

Yeah, it's due to power renegotiation.

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.

Re: USB Power Delivery: Plugging into the Benefits

#74

Post by mtabini »

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.

USB-PD 3.1 provides both a Get_Battery_Cap message, which asks the sink to tell the source the capacity of its battery) and a Get_Battery_Status message, which asks the sink to inform the source about the current charge of its battery.

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!

Re: USB Power Delivery: Plugging into the Benefits

#75

Post by chocolatkey »

ranger207 wrote: post #55
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

Which startech product did you end up getting? One of the hubs or chargers? I have a similar issue with various USB-C rack devices

Re: USB Power Delivery: Plugging into the Benefits

#76

Post by quotemstr »

I'm appreciating this recent spate of "Why Underappreciated Technology X is Good" articles. (For example, the recent EXIF one.) It's way too easy focus on the bad and foment outrage. But the world we inhabit is pretty good, and it's good to understand why it's pretty good.

Re: USB Power Delivery: Plugging into the Benefits

#77

Post by [deleted] »

exmadscientist wrote: post #18
duskwuff wrote: post #17

Earlier quoted context omitted.

> By "that mode", do you mean "1.5A @ 5V" permitted by BC 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.)

The A-to-C cable often does not work because the resistors are supposed to be in there . So if you are having complete charge failures, try a different cable.

[deleted]

Re: USB Power Delivery: Plugging into the Benefits

#78

Post by megous »

seba_dos1 wrote: post #53
megous wrote: post #19

Earlier quoted context omitted.

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.

It's certainly not easier. Type-c power sink can advertise USB default, 1.5A or 3A easily. USB default is not necessarily underpowered. You still have to use BC1.2 to see if the source is actually underpowered.

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.

Re: USB Power Delivery: Plugging into the Benefits

#79

Post by seba_dos1 »

megous wrote: post #78
seba_dos1 wrote: post #53

Earlier quoted context omitted.

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

It's certainly not easier. Type-c power sink can advertise USB default, 1.5A or 3A easily. USB default is not necessarily underpowered. You still have to use BC1.2 to see if the source is actually underpowered. 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…

It sure is. You can just spec it to require a USB-C 7.5W/15W source and then you can gate the operation behind a simple analog circuit and Bob's your uncle. No such way with microUSB until you implement BC1.2, which you don't have to support with USB-C (though it's certainly nice when you do).

> 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.

Re: USB Power Delivery: Plugging into the Benefits

#80

Post by contingencies »

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

Existing solution @ https://github.com/vk2diy/hackbook-m4-mini
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