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Hackers Can Now Trick USB Chargers To Destroy Your Devices

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asmi:

--- Quote from: blueskull on July 22, 2020, 08:31:17 am ---https://www.oppo.com/en/newsroom/press/oppo-launches-125w-flash-charge-65w-airvooc-wireless-flash-charge-and-50w-mini-supervooc-charger/

--- End quote ---
That page seems to be full of marketing BS. First of all, USB PD only goes up to 100 W (20V@5A), and even that is only with EC-marked cable certified to withstand 5 A current - non-EC cables are only allowed 3 A, so 60 W max. Second - what kind of battery will be able to take such huge charging current without exploding anyway? I have S9+ phone, and it's "quick charge" is only 5V@2A, so 10 W total (measured it on 45 W USB-C PD power supply which I use for my own USB-C PD development). USB-C allows up to 5V@3A (15 W) without all of that PD business, with a simple pair of resistors. I'm yet to actually hold in a hand a phone that raises the charging voltage above 5 V, but USB-C spec requires all devices to withstand 20 V regardless of what it actually needs or uses. It also needs to withstand 20 V on CC lines (because these lines are right next to Vbus ones, so they might get connected for a moment during connection/disconnection). USB PD sinks are required to ensure Vbus voltage is Vsafe5V before they proceed with any power negotiations, and a "charger-that-is-stuck-at-20V" is a recognized failure mode that all USB-C compliant devices need to be able to handle. Finally, building a reliable over-voltage protection is not a rocket science - polyfuse + crowbar circuit were invented a long time ago.

SilverSolder:

--- Quote from: Berni on July 23, 2020, 04:13:35 pm ---I think its more the case that a load dump would blow up a cheap cigarette socket USB charger since most are not all that well made. And the failure mode of buck DC/DC converters is often to just let the full input voltage trough. Still a load dump is rather rare is likely to fry something else too.

But yeah its ridiculous to try and design a phone to handle that. I do think it would make sense to survive 24V if you have a USB-C port on the phone. But i can see why a lot of phone manufaturers wouldn't bother with the extra cost and the effort to find room inside the phone for an additional bulky power IC.

--- End quote ---

Does the protection have to be anything fancier than a mosfet pass transistor that can block the current?

asmi:

--- Quote from: blueskull on August 13, 2020, 02:37:24 pm ---It is not PD.
--- End quote ---
Yes, I said above - it's BS, not PD.


--- Quote from: blueskull on August 13, 2020, 02:37:24 pm ---Just about every Chinese phone and the yet to be released iPhone 12 have joined this war of number. 40W is practically the minimum. Samsung is lame.
--- End quote ---
Chinese are known to not care about safety as much as they rest of the world. You might want to read up on where this 20V@5A limit came from - this is not just a random number.


--- Quote from: blueskull on August 13, 2020, 02:37:24 pm ---USB is an open standard, meaning USB-IF has no legal ways of mandating compliance. You will be surprised at how few things are actually USB compliant in everyday life.
--- End quote ---
Technically they do - you are only supposed to put USB logo on compliant devices. Whether they actually do it is a separate discussion.


--- Quote from: blueskull on August 13, 2020, 02:37:24 pm ---Try building a 40W+ power path with 99.x% efficiency requirement with 5x overvoltage protection in the very limited left over space (apart from huge SoC, memory, storage and RF chips) on a phone motherboard and open my eyes.

--- End quote ---
I don't see a big problem doing so. But again, there is no need to do so as every USB-C device is required to withstand 20 V - like I said above, this is a recognized failure mode that needs to be tested for in order to be compliant, and no firmware on a PS can cause it to output higher than 20 V as it's a HW limitation.

asmi:

--- Quote from: blueskull on August 13, 2020, 03:08:30 pm ---Who cares if it is PD? What makes you think only USB-IF endorsed power delivery schemes are allowed? This VOOC thing has nothing to do with PD.
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I do. Whatever you think about USB-IF (and I have my reasons to dislike them to put in mildly), the big advantage of PD is it's universality. I can connect any PD charger to any USB-C device and know that one of two things will happen -1) it works/charges, even if perhaps slowly, or 2) it doesn't work and complain about insufficient power. But most importantly, I know that one thing will absolutely NOT happen - either device will receive a permanent damage.


--- Quote from: blueskull on August 13, 2020, 03:08:30 pm ---The law says okay, technically it is okay, and the market people thinks it is a good feature, so why not make it? War of numbers, this is what drives consumer electronics to develop.
With enough market incentive and legal workaround, more radical solutions will be proposed. It is not about if, it is about when. Welcome to capitalism.
--- End quote ---
The law doesn't say it's OK. That's the point. Like I said - go and read up on where USB PD limit came from.


--- Quote from: blueskull on August 13, 2020, 03:08:30 pm ---Then there would not be so many dead "tri star" chips on Apple products.
Since the type C trend, every device shows the same spike of failure mode of USB-C PMIC blowing up.
I'm pretty sure PMIC designers of Maxim/TI/whatever are smarter than most of us.

--- End quote ---
Apple are known to cut corners on their HW, and pretty much any of their device has at least some kind of HW fuck up. So they are hardly a good example. I evaluated a few USB PD power controllers, and all of them were able to handle 20 V just fine. If someone does something stupid, it doesn't mean there is no better way.

asmi:

--- Quote from: blueskull on August 13, 2020, 03:32:31 pm ---Not how it works here. In China we don't care about patents, so chargers you buy here are all so called multi protocol.
It's not common to find a type C charger to do PD, QC, FCP, SCP, AFP, DCP, and more, all in one.
--- End quote ---
I don't care how things work in China. I have enough to worry about in my own country to care what happens elsewhere.


--- Quote from: blueskull on August 13, 2020, 03:32:31 pm ---Just grab a 65W charger and it will work on practically any devices.
--- End quote ---
And what do you do if your phone explodes in your hand due to some kind of incompatibility?


--- Quote from: blueskull on August 13, 2020, 03:32:31 pm ---They can get around with it with warning signs and cable DRM. Vivo sells worldwide, you are welcomed to sue them. I'd appreciate a cut if you manage to make big chunks of money from them.
--- End quote ---
They know better than selling this junk in countries which actually care about their people, and where selling dangerous piece of junk can have serious legal consequences.

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