NineLizards: USB-C / Thunderbolt / USB4 / USB-C Docking Stations

Datatalk / USB Standards.

I needed to figure out what kind of USB-C cable I needed for a docking station, and then things got complicated really fast 😁

So, did you know that you don't need high speed cables if you want to connect (multiple) monitors over USB-C? Or that different combinations of adapters, cables and devices offer different charge speeds because they negotiate -- if they're all new enough, of a decent quality, and have a chip? Read on...

1. Flavors

USB-C comes in many flavors. You can't always deduct all features from the spec sheets nor what's printed on the device or cable. And when it comes to cables there's a lot of 'creative' marketing going on. On top of that, not all implementations are perfect, so things might just not work as you'd expect.

Okay, that's a start 🤔

See here on Benq.com, Wikipedia USB-C and Wikipedia USB-4 for some generic info.

2. Cheap vs. Expensive

Yes, some of the better cables cost a bit more. Sometimes you pay for features, sometimes for the name.

Don't buy snake-oil, but go for mid class mid price. Definitely veer away from the wonky stuff you find on Wish 😜

Be careful with cheap cables and high power charging. You don't want to burn down your house!

I'd suggest to stick to well known brands like Belkin, Cable Matters, Satechi, Ugreen, Anker, and I've never had any issues with (don't laugh) Ikea!

3. Chipped

Most USB-C cables are chipped.

The chip in an USB-C cable tells the world what capabilities the cable has.

Yes, that's right, the first device, the cable, and the next device share what they are able to do, so the worst of the three defines speed, charging, and other alternate mode support (more on that later).

I've seen a few cases where swapping the ends of a USB cable made a difference (?) and even where flipping the connector upside down changed the data speed (??).

Going chip-less

USB-C cables are not required to have a 'chip'.

If they have one, then that chip is telling the outside world what the cable is good for. If they DON'T have a chip, the cable is SUPPOSED to be a regular USB-C cable, limited to 5V 3A 15W charging, and 480 Mbit/sec data.

But... things are not always as they seem, and some cheap counterfeit Chinese stuff may claim to be high speed / high power, yet be slow as a turtle and burn like a glow wire.

Other cables may not spec anything, and have a chip in there that make them charge and transport data like turtles. However, these cable might have a chip that tells the outside world that they are crap, and thus they are compliant. At least they're saver than glow wires!

Buyer beware.

4. Charging - Power Delivery

The basics:

1. Longer cables charge slower.

2. If your cable supports PD (Power Delivery) you're fine. Your cable will not go up in flames
3. Most decent charge cables specify the wattage (for laptop usage this will be typically 45W, 60W, 100W).
4. If the cable is a decent brand but it doesn't specify anything I wouldn't expect anything over 5V 3A 15W

5. If your phone comes with a dedicated high speed charger and cable, I would mark the charger and cable and keep them together. They might use something non-standard

'Charge' cables

Micro-USB charge cables (sometimes called charge only) tended to be long(ish) USB cables only used to charge devices, such as Playstation / Xbox controllers, and things like that. They wouldn't have any data lines.

USB-C charge cables NEED some data links and must support PD to be able to negotiate charging speeds. Typically, a USB-C charge cable indicates that the cable can handle more than 25W, but there's no official definition I could find.

Charge speeds

I'm not entirely sure how low speed charging is implemented in USB-C. I've seen quite a few device / cable / charger combinations limiting themselves to 5V 1.5A 7.5W, so I assume they use PD to negotiate?

Anyway, by default USB is limited to 5V 500 mA per port.

When the two devices can make up their mind it might be 5V 900 mA.

There are some non-standard, brand specific handshakes (mostly for older mobile phones) that would allow higher charging speeds. Those are not part of the standard so let's ignore them.

The lowest charge speed for an USB-C seems to be 5V 0.1A, but I'm not entirely sure as I found several docs that say an unchipped cable MUST support 3A. Maybe a chipped cable could instruct the connected devices to go lower than the default value?

On Android Authority I found this: (click to enlarge)

So, in other words, if you cable supports Power Delivery (a standard which dates back to 2012 I believe) your first device, the cable, and the second device together figure out how much power they can use for charging.

Sometimes different combos of cables and charges may result on one cable charging faster than another, and of course there are some non-standard implementations by phone manufacturers... Sigh.

More info on this page on Android Authority.

The black lightning bolt...

...next to a USB port on your device can indicate:

that this USB port can deliver more power than other ports (often limited to 5V 1.5A or 2.4A)

that this USB port is suitable for charging other devices such as phones, even when your laptop / docking station is switched off

that this USB port can be used to charge your laptop (but that's not always the case, so be careful, RTFM people)

This arrow can also come in other colors, though it's mostly black, and never has an arrow at the tip. Don't mix it up with the Thunderbolt Icon, which is mostly white, and does have the arrow at the tip. See below.