Guide pinout and USB-C features

Guide pinout and USB-C features

USB Type-C is a specification for a USB connector system that is gaining popularity among smartphones and mobile devices and is capable both of which data transmission power delivery.

Unlike his predecessors USB, is flippable, so no need to try three times to connect.

This introductory article will examine some of the important features of USB-C standard.

What is USB-C?

The USB-C is a relatively new standard that aims to provide a high speed transfer data up to 10 Gb / s with power flow capacity of up to 100 W. These characteristics can make USB-C a truly universal connectivity standard for modern devices.

USB-C o USB Type-C?

These two terms are generally interchangeable (use both in this article). Although USB-C is the most commonly used, USB Type-C is the official name of the listed standard USB.org.

USB-C Functionality

The USB-C interface has three main features:

  • It has a swivel connector. The interface is designed in such a way that the plug can be rotated with respect to the socket.
  • It Supports USB standard 2.0, USB 3.0 e USB 3.1 Gen 2. Furthermore, It can support protocols of third parties such as HDMI and DisplayPort in an operational mode called alternative mode.
  • It allows devices to negotiate and choose an appropriate level of current flow through the interface.

In the following sections we will see how these features are provided by the USB Type-C.

The press / spinotto USB Type-C

Figure 1. La presa USB Type-C.

Figure 2. La spina USB Type-C.

USB differential Couples 2.0

I pin D + e D- differential pairs are used for USB connectivity 2.0. There are two pin D + and two pin D into the socket.

However, the pins are connected to each other and there is actually only one pair of USB differential data 2.0 available for use. The redundancy is only to have a rotatable connector.

Pin mass and power

I pin VBUS e GND carrying the power and the return paths for the signals. The default voltage VBUS 5 V, but the standard allows devices to negotiate and choose a different voltage VBUS from the default value. The Power Delivery enables to have a VBUS voltage up to 20 V. Even the maximum current can be increased up to 5 A. Then, the USB Type-C could deliver a maximum power of 100 W.

The high-power flow could be useful when loading a large device such as a portable computer. The figure 3 shows an example of RICHTEK in which a buck-boost converter is used to generate the appropriate voltage required by the notebook computer.

Figure 3.

It should be noted that the dispensing technology of power makes USB Type-C more versatile than previous standards because it makes the power level adaptable to the needs of the load. You can load both smartphones and notebooks using the same cable.

I pin RX e TX

There are two sets of differential pairs RX and two pairs of differential pairs TX.

One of these two couples RX along with a TX pair may be used for the USB protocol 3.0 / USB 3.1. Because the connector is flippabile, a multiplexer is required to properly redirect the data on differential pairs used through the cable.

I pin CC1 e CC2

These pins are the channel configuration pin. They perform a series of functions such as the cable connection and removal detection. These pins can also be used for communications required by the power delivery and the alternative mode.

The figure 4 below shows how the pin CC1 e CC2 reveal the orientation of the intake / spina. In this figure, DFP stands for Downing Facing Port, the door which acts as a host in the transmission of data or from the power source. UFP indicates Porta upstream that is the device connected to the host or to the consumer of energy.

Figure 4.

The DFP pulls on the pin CC1 and CC2 through the Rp resistors but the UFP drags them downwards through Rd. If no cable is connected, the source sees a logic high at pins CC1 and CC2. The connection of the Type-C USB cable creates a current path to it from 5 V earth. Because inside the USB Type-C cable there is only one DC cable, It is formed only one current path. Eg, in the upper graph of Figure 4, the pin of the DFP CC1 is connected to pin CC1 dell'UFP. Then, DFP CC1 pin will have a voltage of less than 5 V but the DFP pin CC2 will still be at most logical. Therefore, monitoring the voltage on DFP CC1 and CC2 pin, we can determine the cable attachment and its orientation.

Besides the orientation of the cable, Rp-Rd path is used as a way to communicate information on the capabilities of the current source. A tal fine, the energy consumer (UFP) monitors the voltage on the DC cable. When the voltage on the DC cable has the lowest value (circa 0,41 V), the source can provide the default USB power that is respectively 500 but it is 900 mA for USB 2.0 e USB 3.0. When the DC line voltage is about 0,92 V, the source can supply a current of 1,5 A. The highest DC line voltage which is about 1,68 V corresponds to the current capacity of a source of 3 A.

The pin VCONN

As mentioned earlier, the USB Type-C aims at providing fast data transfer speeds and high power flux levels. These features may require the use of special cables that are marked electronically using a chip inside. Furthermore, some active cables use a re-driver chip to enhance the signal and compensate the losses suffered by the cable, etc. In these cases, we can supply the circuits within the cable by applying a direct voltage of 5V, to provide power to the pin VCONN. This is shown in Figure 5.

Figure 5

As you can see, the active cable uses the resistors Ra to lower pin CC2. The Ra value is different from Rd, then DFP is still able to determine the orientation of the cable by examining the voltage on the DFP CC1 and CC2 pin. After determining the orientation of the cable, the channel configuration corresponding to pin “Active Cable IC” It will be connected to a power supply 5-V for powering the circuits within the cable. Eg, in the figure 5, Rp-Rd valid path corresponds to the pin CC1. Then, CC2 is connected to the pin indicated by VCONN.

I pin SBU1 e SBU2

These two pins correspond to the low-speed signal paths that are used only as an alternative mode.

The USB Power Delivery

Now that we are familiar with the pinning of the USB-C standard, let's look at the USB Power Delivery.

As mentioned earlier, the devices that use the USB Type-C standard may negotiate and choose an appropriate level of current flow through the interface. These power negotiations are implemented through a protocol called USB Power Delivery which is a single wire communication on the DC cable discussed above. The figure 6 below shows an example of a USB power supply in which the sink sends requests to the source and adjusts the VBUS voltage according to necessity. At first it is required a 9-V bus. After that the source has stabilized the bus voltage to 9 V, send a message “ready for feeding” to receiver. Then, this requires a 5-V bus and the source provides it and sends back a message “ready for feeding”.

Figure 6.

It `s important to note that “USB Power Delivery” not only about negotiations relating to energy supply, other negotiations, such as those relating to the alternative mode, They are performed using the protocol Power Delivery on the DC cable.

alternative Ways

This mode of operation allows us to implement third-party protocols, come DisplayPort e HDMI, using the standard USB Type-C. All alternatives mode must support at least one USB connection 2.0 e USB Power Delivery. For more information, refer to this document TI .

Conclusion

USB Type-C has interesting features. It supports a transfer rate of fast and brilliant data up to 10 Gb / if a high power flow up to 100 W. These connectors can make very small USB Type-C a truly universal standard for modern devices.

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