What is USB TYPE-C (below)

Publish Date:2016-10-27 | Hits: | 字号:

    Connected to an article, in March 2015, Apple released a new MacBook, using a USB Type-C, a move that led to industry hot, Apple has never given up its closed system, means that TYPE-C interface is expected to unify all Mobile phones, flat panel, PC and other equipment, wired interface, in the era before the end of the cable, forming a unified interface and cable. Let us in-depth understanding, TYPE-C interface to the actual structure of the internal, explore its series of magical properties of the origin. 


First, let us directly from the USB TYPE-C Spec on a USB TYPE-C female pin pin diagram to see:



Figure 1 USB TYPE-C female base pin diagram from the USB TYPE-C SPEC


    Can be seen, the mother has 24 signals, including power and ground to occupy the eight, to enhance the current transmission capacity, and the remaining 16, for the transmission of USB2.0 two signals are cross-linked, remove duplication Of the two, a total of 14 signals. Including the two groups we are familiar with a total of eight can be used to transmit usb3 data RXx and TXx, USB2.0 data signals D +, D- and SBU1, SBU2, CC1, CC2. Which SBU1, SBU2, CC1, CC2 is the traditional USB interface does not have the signal. CC is the soul of the USB TYPE-C interface. It carries the confirmation of the transmission direction and the positive and negative insertion confirmation function during the TYPE-C connection, and the USB PD BCM code signal transmission function to realize the function configuration of the load. Two CC lines, when one of the CC as TYPE-C interface configuration signal, the other CC as the cable EMARKER chip power supply. The remaining SBU1 and SBU2 are auxiliary signals and have different uses in different application scenarios. For example, in the ALT MODE mode for DP signal transmission, as the audio transmission channel, into the TYPE-C analog audio headset accessory mode, as the microphone signal transmission channel.


So, was mentioned up and down the positive and negative insert, is how to achieve it? The secret lies in the CC male head. Let us look at the structure of the CC male head.



    Figure 2 TYPE-C male signal structure


Comparing the wiring diagram of the mother, we can see that the male has only one CC and the other CC becomes the VCONN, so when the male is inserted into the female, the CC on the male connector may be connected to the CC1 on the female Together with the CC2 may also be connected with the mother, respectively, corresponding to the positive insert and anti-insert two cases. The mother of the need to use a chip to detect the establishment of a CC1 connection, or CC2 established a connection to control the equipment inside the SWITCH, to the correct adaptation of data transmission, or audio and video transmission signal correspondence.


After understanding the transmission interface structure and the principle of positive and negative identification, we take a look at the details of current transmission problems, according to USB-IF standard, the version of the USB interface, the current transmission capacity is as follows:


USB 接口电流传输能力

Figure 3 USB standard-level maximum transmission power from USB TYPE-C SPEC


USB Type-C does not necessarily support 20V / 5A. By default, it only supports 5V3A. It must support USB PD communication capability and Emarker chip on the transmission line. In this case, it is possible to support 20V / 5A. Of course, relative to the development of standards for the difficulty of this work itself, the design of USB PD chip and EMARKER chip is a piece of cake. Under normal circumstances, the standard will be released within six months after the sample, a year will be mass production. For example, the country already has to support CC logic LDR6013 chip, and support for USB PD LDR6021 and LDR6023 chip.

Power transmission, has been understood, let us look at the specific data transmission. In the traditional TYPE-A USB3.0 interface, there is a group of rx and a group of tx, a total of four high-speed signal transmission line, the maximum transmission 5G bandwidth signal. The TYPE-C interface, then a total of two sets of rx and two sets of tx, a total of eight high-speed signal transmission line, which is considered positive and negative interpolation, for USB3.0 signal transmission, which only use one group. In addition, it can be used separately, using the PD negotiation, into the ALT mode, the four for the transmission of USB3.x signal, the other four and sbu1 and sbu2 together for the transmission of 2 lane DP signal. Can also be negotiated into eight differential lines, and sbu1, sbu2 combination, all for the transmission DP signal. This is 4lane DP signal, the highest resolution can be up to 8K. These flexible applications, so that type-c interface has been given unlimited possibilities. In the final analysis, is able to carry out power, data, audio and video transmission, and transmission than the old transmission line performance is better. Really is someone else's way, so that others no way out. Of course, TYPE-C although such cattle B, but do not forget, there is another cable transmission master, that is, fiber. Its transmission limit bandwidth, according to T (1000G) to calculate. Moreover, the existing TYPE-C power transmission capacity and sufficient to support fiber MODEN. So, if the existing TYPE-C cable, based on the eight high-speed signal transmission line replaced by a fiber, who knows what will happen?


Summary, USB Type-C end USB has long been tried to repeat the trial and error method to repeat the history, saving people a lot of time, change the direction of at least 2s, according to the global one billion people a day plug USB, 50% probability of inserting the wrong, total time-consuming more than 277,000 hours, about 31 years, too horrible. An interface to get the power, data, audio and video data transmission needs of three, small size. Can be expected, after the phone can be changed to USB Type-C interface, and if only USB2.0, then only need to redo the cable, some features need to add the interface chip, the cost can be completely negligible. While the phone to USB3.0, the real revolution will appear. PC may no longer be required, a mobile phone, through the TYPE-C port output DP, access to the computer monitor can complete the function. If connected to VR, then the whole world is different. I ask, who would need a PC, laptop, such 20th century heritage?


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