USB Type-C and power delivery 101 – Ports and connections

May 08, 2017

gaya-May 08, 2017

USB Type-C is the newly introduced and powerful interconnect standard for USB. When paired with the new Power Delivery (PD) specification, Type-C offers enhancements to the existing USB 3.1 interconnect that lower the cost and simplify the implementation of power delivery over USB.  From a form factor perspective, the USB Type-C connector combines multiple USB connectors – Micro-B, Type-A, and Type-B – in a reversible connector measuring only 2.4 mm in height (see Figure 1).  Type-C allows developers to also combine multiple protocols in a single cable, including DisplayPort, PCIe or Thunderbolt.  Bandwidth is double that of USB 3.0, increasing to 10 Gbps with SuperSpeed+ USB3.1.  Finally, the USB Type-C connector can deliver up to 100 W.  This enables a wider range of applications to operate using USB (see Figure 2).  For more details, watch An Introduction to USB Type-C video and Type-C Basics.

In this two part series, we describe power delivery with USB Type-C, starting with ports and connectors in this article, followed by the power delivery protocol in part two.


Figure 1. USB Type-C: Connector of the Future (Source: Cypress Semiconductor)  


Figure 2. Power Delivery enables a wider range of applications (Source: Cypress Semiconductor)  

USB Type-C Protocol View

USB Type-C Signals

Figure 3 show the USB Type-C Receptacle and Plug signals. Table 1 and Table 2 summarize the list of signals used on the USB Type-C interface (receptacle and plug) as defined by USB Type-C specifications.

click for larger image

Figure 3. Type-C Reversible Connections (Source: Cypress Semiconductor)  

 

Table 1. USB Type-C Receptacle Signals (Source: Cypress Semiconductor)

Signal Group

Signal

Description

USB 3.1

TX1p, TX1n RX1p, RX1n

TX2p, TX2n RX2p,RX2n

The SuperSpeed USB serial data interface defines a differential transmit pair and a differential receive pair.

On a USB Type-C receptacle, two sets of SuperSpeed USB signal pins are defined to enable the plug-flipping feature.

USB 2.0

Dp1, Dn1

Dp2, Dn2

The USB 2.0 serial data interface defines a differential pair. On a USB Type-C receptacle, two sets of USB 2.0 signal pins are defined to enable the plug-flipping feature.

Configuration Channel

CC1, CC2

The CC channel in the receptacle detects the signal orientation and channel configuration.

Auxiliary Signals

SBU1, SBU2

Sideband Use. SBU signals are used in the Alternate Mode supported by the Type-C specification, which enables multi-purposing of Type-C signals for alternate uses such as DisplayPort

Power

VBUS

USB cable bus power

GND

USB cable return current path

Table 2. USB Type-C Plug Signals (Source: Cypress Semiconductor)

Signal Group

Signal

Description

USB 3.1

TX1p, TX1n

RX1p, RX1n

TX2p, TX2n RX2p,RX2n

The SuperSpeed USB serial data interface defines a differential transmit pair and a differential receive pair.

On a USB Type-C receptacle, two sets of SuperSpeed USB signal pins are defined to enable the plug-flipping feature.

USB 2.0

Dp, Dn

The USB 2.0 serial data interface defines a differential pair. On a USB Type-C receptacle, two set of USB 2.0 signal pins are defined to enable the plug-flipping feature.

Configuration Channel

CC

The CC in the plug used for connection detection and interface configuration

Auxiliary Signals

SBU1, SBU2

Sideband Use. SBU signals are used in the Alternate Mode supported by the Type-C specification, which enables multi-purposing of Type-C signals for alternate uses such as DisplayPort

Power

VBUS

USB cable bus power

VCONN

Type-C cable plug power

GND

USB cable return current path

The USB Type-C Receptacle functionally delivers both USB 3.1 (TX and RX pairs) and USB 2.0 (D+ and D−) data buses, USB power (VBUS), ground (GND), Configuration Channel signals (CC1 and CC2), and two Sideband Use (SBU) signal pins.

To enable Type-C cables to be reversible, the Type-C receptacle is fully symmetrical. All power, ground, and signal pins are duplicated about the symmetry axis, which allows the Type-C plug to be flipped with respect to the Type-C receptacle. The Type-C plug offers only one CC pin, which is connected to one of the CC pins of the Type-C receptacle, to establish the Type-C orientation. The other CC pin is repurposed as VCONN (abbreviation for VCONNECTOR) for powering the electronics in the USB Type-C plug.

When the Type-C plug is rotated (as shown in Figure 3):

  • GND, USB 2.0 and VBUS signals maintain connection. USB 2.0 signals are repeated in the top and bottom rows of the Type-C receptacle to maintain connectivity in either orientation.

  • VCONN or CC pin on the plug may be connected to either of the configuration channel pins – CC1 or CC2 of the receptacle – depending upon the orientation.

  • One of the two Superspeed lanes maintains the right connection, which must be appropriately routed at the receptacle side using a SuperSpeed mux.

Continue reading on page two >>

 

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