What is an USB4 E-Marker

The specifications before Type C (TypeA,TypeB,etc.) focus on the "hard" characteristics of USB interface, such as the number of signals,the form of interface,electrical characteristics,etc. On the basis of defining the "hard" feature of USB interface, TypeC adds some "soft" content. USB interface (only refers to TypeC) gets rid of the subordinate relationship with USB and becomes a new specification that can be on an equal footing with USB specification. After USB was upgraded to version 3.1, all physical interfaces adopted Type C structure, and the actual 3.1 standard USB Type-C wire structure was not unified, which caused a lot of confusion. Until 2019, in order to standardize their functions and electrification performance, the association set a threshold. If the products want to support 5A high current E-marker chip is required for USB 3.0 or higher transmission speed and video output function. E-MARK, full name: electronically marked cable, USB Type-C active cable encapsulated with E-marker chip. DFP and UFP can read the properties of the cable by using PD protocol, including power transmission capacity, data transmission capacity, ID and other information. In short, if the Type-C data line is equipped with E-marker chip (we call it electronic label), This chip can communicate with USB port through USB power supply specification 2.0 BMC protocol. The electronic tag cable can be powered by vconn or directly by VBUS, and can consume up to 70mW of power.

Compatible with USB3.1 USB Type-C cable, 100W power supply cable. Any cable that can realize the power carrying capacity of more than 60W must have an electronic label and be able to communicate with the DFP port. If a cable with an electronic tag is inserted into a socket that does not support USB power supply specification 2.0, its behavior is exactly the same as that of a standard passive cable.

E-MARK chip of USB4

E-marker (electronically marked cable) can be simply understood as the electronic label of Type-C line. The set functional attributes of the cable can be read through the E-marker chip, such as power transmission, data transmission, video transmission and ID. Based on this, the output terminal can adjust the matching voltage / current or audio and video signal according to the connected equipment such as mobile phone or display. In the past, E-marker chips have always been imported. Cypress and Intel have strong products of E-marker chips. Apple once customized E-marker USB4 chip JHL 7040 to Intel for use on Thunderbolt interface. In recent years, with the efforts of some domestic companies, domestic E-marker chips that can support USB4 have also begun to be commercially used. In October 2020, Chengdu Yichong semiconductor launched the first E-marker chip CPS 8821 in the mainland and the fifth E-marker chip certified by USB-IF USB 4 in the world. Since then, many companies have also launched related products on the E-marker of USB4.

At present, some E-marker product models supporting USB4 have been released:

The first principle of using E-MARK: if you want to provide more than 5V voltage or more than 3A current through USB type-C interface, you must need Type-C interface chip to realize USB PD protocol

The second principle of using E-MARK: if your equipment uses 5V voltage and does not exceed 3A current. It depends on the power supply characteristics and data transmission characteristics of the equipment itself. If the equipment itself only supplies power to the outside or only receives power from the other party, and the power supply role and data transmission role are matched by default (that is, the power supplier is host and the power consumer is slave or device), then you don't need type-C chip

The third principle of using E-MARK: these two principles are used to judge whether Type-C chip is needed on the equipment. Another point of concern is whether E-marker chip is needed on the C-C transmission line. The judgment standard is whether the current will exceed 3A during use? If not, you don't need a to C and B to C lines. See whether you need to implement the battery charging protocol. If you want to implement it, you can use LDR6013. The advantage is that it can not only realize charging, but also transmit data, so as to avoid the problem that some adapters that do not comply with the Battery Charging protocol can't charge Apple devices

Chip knowledge in cable industry

Today's USB data lines are beginning to need application chips. If a USB type-C data line is needed, it is necessary to realize efficient data transmission, high-definition video transmission and strong equipment power supply. The ability of the chip is needed to help support multiple high-speed interface protocols, including USB4, DisplayPort 1.4A TX, PCI Express and Thunderbolt 4, which is bound to need the support of the chip, The USB4 router IP constructs the effective connection between all supporting protocols through the chip. The USB4 wire needs an IC, one is to ensure the quality of high-speed signal transmission, and the other is to store the relevant information of the cable, including whether it can support the on-board current from 3a to 5A. Because the speed of signal transmission is faster now. At present, the fastest single channel transmission can reach 20gbps, and the wire can not be too short. In order to ensure the signal quality, chips with functions such as re timer and re driver are generally added. Re-timer is used to recover data, and re-driver is used to enhance the signal of attenuation and consumption, This kind of IC can ensure the accurate and stable transmission of high-speed signals within the specified distance. Another kind is the E-MARK chip we are talking about today, which supports USB PD protocol communication. By communicating with this chip, we can not only know the ID information of the cable, but also know whether the supported current can exceed 3a, so that we can distinguish between cables with high current and cables below 3a. It can not only meet the use of high current, but also protect cables below 3a. In the era of USB 3.0, the maximum transmission speed is 5Gbps, and the carrying current will not exceed 3a, so there is no need for the above IC. In the future, with the upgrading of products, more and more chips will be applied to products, so don't misunderstand that the chip of USB4 products is just E-MARK chip.

Type-C related industrial chains have attracted much attention

In the 5G era, with the improvement of hardware performance and the enrichment of application scenarios, the power consumption of mobile phones has become larger and larger, and the endurance ability of mobile phones is facing challenges again. Limited by the internal space, weight and safety of mobile phones, the battery capacity of mobile phones cannot be increased endlessly. Fast charging has become the only way to solve the problem of battery life. Since 2018, mobile phone fast charging has gradually increased from 18W to 40W or even higher 65W. This year, the mobile phone industry is expected to enter the 240W fast charging era, so its technical difficulty is raised again, and challenges and opportunities coexist.