The USB Revolution

September 4, 2014

The USB.org just released the new USB 3.1 specifications that includes the updated Power Delivery 2.0 Specifications and the new Type-C connector Specifications.

This big update can be considered a revolution in the USB ecosystem, as it introduces not only mechanical modifications of connectors and cables, but new interfaces and new features, too. It’s a sharp discontinuity with the past and it will have a big impact in the consumer market of USB devices, chargers and peripherals.
It will change the scenario around your desktop, the way you will charge your mobile devices, the way you will manage the peripherals like monitors and printers.

Type-C Connector

The main contributor of this revolution is the new Type-C connector and cable. The specifications (Revision 1.0, August 11, 2014) define a robust, small (more or less the same size of a micro-USB connector), flippable 24-pin connector.


The respective Type-C cable contains up to 19 wires:

  • 2 Power GND (mandatory)
  • 2 Power VBUS (mandatory)
  • 1 shield (mandatory)
  • 1 Configuration Channel (mandatory)
  • 1 unshielded pair for USB 2.0 (mandatory)
  • 2 shielded pairs
  • 2 reserved for future use
  • 1 Power VCONN

The 2 shielded pairs are used to implement USB 3.1 10 Gbit/s transfer but they can be used for other interfaces like audio for headsets, Display Port for video exporting or other customized interfaces. This flexibility is a great news in the USB scenario: new protocols can be carried over USB simplifying connections around PC and mobile devices.
The configuration channel (cc) is reserved for USB Power Delivery Protocol used not only for power negotiation but for role negotiation (the up/downstream role is not anymore defined by the connector type, as you can have Type-C plug in each end of the cable), interface definition and active cable communications.

update: good article about Type-C connector with photos and speed tests.

USB Power Delivery

The USB Power Delivery has been updated taking in account the Type-C implementation. A dedicated wire (cc ) is reserved for this communication with a new physical channel in base-band (USBPD-BB). The earlier powerline communication over VBUS using FSK modulation (USBPD-FSK) is not anymore required. This physical layer is anyhow still existing and it’s mandatory for Type-A and micro A/B connectors.
The USB Power Delivery protocol has been extended with new functions and commands to support the new Type-C features.


The new USB Power Delivery specifications and the introduction of the new Type-C connector/cable constitute a revolution in the mobile and PC markets.
The semiconductor ecosystem is moving fast to deliver silicon and hardware solutions for this new technology.

The first product in the market adopting the Type-C connector? Most probably a mobile smartphone but we could wait till beginning 2015. Maybe….


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