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Some Reversible USB-C Cables/Adapters Could Cause Irreversible Damage
TheRealHocusLocus writes: Three Decembers ago I lauded the impending death of the trapezoid. Celebration of the rectangle might be premature however, because in the rush-to-market an appalling number of chargers, cables and legacy adapters have been discovered to be non-compliant. There have been performance issues with bad USB implementation all along, but now — with improved conductors USB-C offers to negotiate up to 3A in addition the 900ma base, so use of a non-compliant adapter may result in damage. Google engineer and hero Benson Leung has been waging a one-man compliance campaign of Amazon reviews to warn of dodgy devices and praise the good. Reddit user bmcclure937 offers a spreadsheet summary of the reviews. It's a jungle out there, don't get fried.
Timothy you've mentioned this before..
http://hardware.slashdot.org/s...
Minimum threshold fixed. Thanks!
This is a new development. Benson Leung found a cable so bad it destroyed his analyzing equipment, and he says he won't be able to do reviews anymore because of it. The cable was actually missing wires internally, among other things.
"First they came for the slanderers and i said nothing."
When it comes to USB, test your equipment, even if you haven't upgraded to Type C yet.
I've personally discovered two counterfeit or substandard (depending upon your personal definitions of the terms) USB charging cables.
What I use to test is a Samsung Galaxy Tab 3 10-inch tablet. This tablet wants approximately 0.7-0.8 amps at 5 volts, but it will charge in a degraded mode if the charging cable isn't up to snuff, or if it's plugged into a desktop or laptop (which normally only supply 0.5 amps).
Every cable should begin by charging in the degraded mode when plugged into my laptop and then upgrade to normal charging mode when plugged into any of my half dozen or so 2 amp USB chargers. Among over a dozen cables, I detected two that were not up to snuff, and you'd be surprised at my results. One cable from the dollar store was garbage, but another, colored cable from the dollar store that had fancy LEDs was fine. Three 10 feet cables were fine. The other reject was an average-looking cable with an average feel. It did not appear to be substandard or counterfeit.
If you want to get fancy you can get a device from banggood.com that measures current and voltage across the USB port. They cost about $3 shipped. That is how I determined that my tablet will draw approximately 0.7-0.8 amps. From that experience I'd be surprised if many devices actually draw a full 2 amps. It's nice to have a 2 amp supply, though, because it gives you a safety factor if your cables are somewhat substandard. Maybe the newest 2016 phones will draw close to 2 amps. Get the meter and find out!
Based upon my experience, the best USB chargers are from Samsung and anything else that has a counterfeit-resistant UL sticker. And also based upon my experience, if you notice that a charging cable is getting warm, you should probably replace it because it's dissipating electricity as heat rather than conducting it.
The missing wires weren't the really bad part - the result of that would've "merely" been that it wouldn't work as a USB3 SuperSpeed cable and only connect in USB2 High Speed mode.
What really set that one apart was that it had VCC and GND swapped on one end.
TFA's title is mislieading. The cable in question was wrongly wired. If you connect GND to V+, and V+ to GND, bad things *will* happen even with USB 1.0.
what was your point, exactly ? https://www.choice.com.au/elec...
ahem... http://www.ibtimes.com/apple-r... http://bgr.com/2014/06/13/ipho... http://bgr.com/2015/06/03/appl...
A quick analysis of the workbook by TheRealHocusLocus finds that "Approved" cables cost ~60% more than unapproved cables on the average.
Apprvd Average of Cost
NO $10.61
Yes $16.71
-- Jared
I would like to correct you on the "cheaped out" as the guy already found and owns several quality cables. It was his choice to spend his time evaluating various cables from a litany of manufacturers to see if they complied with the USB specifications, hardly a case of trying to be cheap. As for the "POS" device, the power rails of the USB port are hooked up to several internal circuits. Most of which can survive a lot of abuse, but reverse voltage is not one that all the components lived through. In fact, if you look through the datasheets for most components you will quickly realize that being able to survive reverse voltage is actually somewhat rare. Fuses would have done squat to save him in this situation.
Also I would advise you to read a bit more closely to his account of how the devices fried. 2 of them went up at once and the 3rd one went in a 2nd attempt. So really it was somewhat understandable that 3 devices were toasted. Though to your point, he (Leung) should have done a continuity check before any of those cables EVER saw a real device. Especially so given that he is purposely buying cables from all reaches of the earth to test them out.
It also doesn't seem like said engineer is waging a holy war. From what I can see he posted it to his own personal G+ page and the news has just been spreading around as various sites picked up on it. I do agree that this is old news, its sad to see that journalism has degraded into retelling the same story over and over.
It's a shame that USB went with Vbus/Gnd rather than V+/V-. The latter would allow the negative side to drift away from ground (which is typically kept on the shield in a zero-current path). They had to devote a small section to voltage drops it in the latest spec (3.6.10.1 in USB_PS_R2_0 V1.1: bottom line is 375mV of Gnd rise and 625mV of Vbus drop).
The Ethernet guys realized this would be a problem so they made their signals transformer isolated. But USB is designed for short runs and cheap interfaces, not 100m runs across different electrical grids.
Note, however, that this case was not related to the ground potential at all. Vbus and Gnd were reversed, exceeding the Vgnd_drop limit by over 9V (2400%), or possibly 40V (>10000%) if the device had managed to negotiate the new voltage limits before it died.
https://en.wikipedia.org/wiki/...
Moderating "-1, Disagree" is simple censorship. Have the guts to post your opinion.
There is an organization that certifies USB stuff. If a cable has a little sticker with that certification logo, it's probably good.
Not sure how much they do to prevent unauthorized use though.
... also, I can kill you with my brain.
The second one is the device is dropping voltage and consuming power. In standard USB with 500mA at 5V, if the MOSFET takes 1V, that's half a watt of power you're losing in the transistor. (And really, you just use a diode). USB-C with up to 100W, you're looking at losing a lot of power in your reverse protection components.
100% wrong.
The MOSFET is not a diode. Diodes DO cause a 0.6-1V drop. That's why they use a MOSFET instead here in applications where a diode drop is too much. The MOSFET only drops as much as its internal Ron on-resistance allows. For a high-grade MOSFET, that can be in the single milliohms, so it's effectively a dead short. Cheapo MOSFETs are still in the low tens of milliohms. So with 3A of power, that's 1/4W with a crappy 30mohm MOSFET, or 72mW with one with a 8mohm on-resistance. The only reason you'd leave this out if reverse polarity is at all possible is cheapness.