Just reviewed a recent spec for Type C cable and connector R2.0 August 2019. Have to admit I didn't read all 373 pages.

Because USB-C is so important to virtually every consumer electronic device vendor, the specification has to be a collaboration between vendors. I counted six pages of vendor contributors in the spec. Each vendor wants to be represented because 1. They want a heads up so they can get started on their implementation 2. They want to be able to lobby the committee to add features that benefit them. 3. It is good to be known as a founding member of USB-C.

Vendors have to pay employees to participate in formal meeting and of course endless emails and conference calls to hammer out the spec. It is a large financial commitment for these vendors.

The spec is made of all two major parts, mechanical and functional. Mechanical means the size, shape and pin-out of the connectors and the wire in between. The functional spec is much more detailed since usually the electronics signals on one end is not necessarily controlled by the same vendor. Typical example, you can buy a non Samsung charger from Amazon to charge your phone and they will work together because of a previously agreed upon specification. That specification being the 373 page spec from the USB 3.0 Promoter Group.

Mechanical Spec highlights from the 2.0 V Spec

As you probably know both sides of the connector are the same so they can be reversed when you plug it in. The spec has a pictures of the connector on pages 42- 55. From these pages a manufacturer can make the connector within stated manufacturing tolerances.

Inside the connector housing there is a male connector. It has a A side and a B side which are a mirror image or nearly mirror images. There are twelve pins on each side for a total of 24 possible connections. There are 4 grounds two each side. 4 power connectors. The rest of the pins handle data. With 24 possible connectors, the cable could have 24 wires. It is highly unlikely there would be 24 wires. With 4 grounds, typically those would be one wire. Same goes for the 4 bus power connectors. Chances are vendors will not wire every data connector either. In typical cases, these USB-C connectors will have less than six wires in use.

Functional Spec Highlights

The functional specification is 235 pages long in this specification. As you probably know a USB cable can be used to charge a device or exchange data or a little bit of both.

Exchange of data is inherently noisy. As the data is compressed to enhance throughput, noise increases and techniques need to improve to separate the signal from the noise. By far, filtering out noise during data exchange is the biggest challenge.

The internal connector has temperature limits to manage. Electrical flow due to charging or data can heat up the connector beyond physical specifications. USB C cables are rated for up to 100 watts. 100 watts is a a lot of power for a handheld device.

Function: USB power delivery or PD

A popular new feature is PD. From the spec.

Essentially managing power levels and sources. USB has had 5 V levels, whereas PD allows up to 20 volts.

• Establish power contracts that allow voltage and current beyond existing USB data

bus specifications.

• Change the port sourcing V BUS .

• Change the port sourcing V CONN .

• Swap DFP and UFP roles.

• Communicate with cables.

USB is short for Universal Bus Description

A bus architecture simply means USB cables can be plugged into the same hub and cooperate exchanging data from/to separate sources. A hub could also be called a Bus.

The spec advises vendors on a common set of rules about exchanging signals and power over 235 pages of specifications. Some highlights include how to handle Audio Data, Digital data and power,

USB-C is the latest connector and cable with the goal to find a Swiss army knife to connect different consumer devices together. As consumers were are lucky to have such a well designed device.

Owen, thank you for a great article about such a useful device to connect up our stuff.

Computer engineer in Silicon Valley. Writing about topics that interest me and may interest you.