The data line also has a "heart" ? What is the use of the E-Marker chip in the USB Type-C cable?

We all know that the USB Type-C interface is inherently capable of data transmission, charging (based on the USB PD protocol) and audio and video transmission. However, the above-mentioned functions have different strengths and weaknesses, and therefore USB Type-C cables of countless specifications have been derived.


Differences in USB Type-C Functionality

Taking data transmission as an example, USB Type-C can choose USB2.0, USB3.0 (USB3.1 Gen1, USB3.2 Gen1), USB3.1 Gen2 (USB3.2 Gen2), USB3.2 Gen2×2 (USB4 20) and USB4 (Thunderbolt 3/4) and other multi-speed standards, corresponding to 480Mbps, 5Gbps, 10Gbps, 20Gbps and 40Gbps respectively.


Taking charging as an example, although USB Type-C cables all natively support 20V voltage, the supported current is different between 3A and 5A. Similarly, the video transmission capability of the USB Type-C cable is also an optional item.



The author made a rough statistics, and there are as many as 13 types of USB Type-C cables matched according to different functional levels, among which the cable that only supports 3A current and does not support data transmission and video output has the lowest cost, we can understand it It is the "beggar's version"), the cable specification supporting Thunderbolt is the most expensive, and it is also the "emperor" of all USB Type-C cables. According to the data in the above table, cables from C to M specifications all have one thing in common, that is, they need a chip called "E-Marker". So what exactly is E-Marker?


The grade depends on E-Marker

USB Type-C should be the most messy cable in history. In order to standardize their functions and electrical performance, USB-IF has set a hardware threshold:

1. Want to support 5A high current

2. Want to support USB3.0 or higher

3. If you want to support the video output function, you need the blessing of the E-Marker chip.

The full name of E-Marker is "Electronically Marked Cable". We can understand it as the electronic identity label of the USB Type-C cable. Through this chip, various attributes of the cable can be read, including power transmission capability, data transmission Capability, video transmission capability, ID and other information. Based on this, the output terminals (such as charging heads, notebooks) can adjust the matching voltage/current or audio and video signals according to the devices connected to the output terminals (such as mobile phones or monitors).

The reason why A and B cables in Table 2 do not need E-Marker is because they only need to pass 3A current, no need to consider the video output capability, and the transmission speed of USB2.0 has no special requirements for cables. However, C~M specifications cannot bypass at least one of 1~3, so they all need to be equipped with E-Marker chips for identification of input/output devices.


It should be noted that the E-Marker chip itself also has different grades. Some only support video output, some only support USB 3.1 Gen1 or USB3.1 Gen2, and some only support 5A current transmission. These E-Marker chips that only support one special function are all low-end. Mid-to-high-end E-Marker chips have a higher level of integration and can support any two or all of the functions in 1~3, and cables that support all special functions can also be called "full-featured."


In the cable sales details interface, the functions and parameter information it supports are usually indicated. But as mentioned above, there are data transmission speeds of 5Gbps, 10Gbps, 20Gbps and 40Gbps, and the video output also supports single 4K@60Hz and dual 4K@60Hz or 8K@60Hz (Thunderbolt), so the full-featured USB Type-C cable There are also strengths and weaknesses, and the higher the specification, the more expensive the price will naturally be.


How to see E-Marker chip

Although the USB Type-C cable has 2 ports at the front and back, generally it is only necessary to embed an E-Marker chip in one of the ports, but there are very few cables that are equipped with 2 E-Marker chips on the ports at both ends , The advantage of dual chips is that the charger has a higher success rate in reading the chips, ensuring stable high-power transmission, and the performance is better when the cable length reaches 2 meters or longer.