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For example, cables that only support 5A charging but not data transmission only need pins connected to VBUS+GND (transmitting 5A current) and CC+VCONN (used for Type-C communication) in the USB Type-C interface.
If you need USB2.0 speed data transmission function, you also need to add D+/D- pins, and the actual number of mailings needs 6. This standard cable has little requirements for interfaces. It only requires 4-layer PCB material made of ordinary FR4 to meet the 5A current transmission level.
However, if it is a full-function cable, on the basis of the former, you need to use TX1+/TX1-, RX1+/RX1-, TX2+/TX2-, RX2+/RX2- and sideband signals SBU1/SBU2 corresponding to USB3.1, and the actual number of mailing lines is at least 16.
In addition, this type of interface also requires the selection of high-frequency and high-performance 6-layer PCB boards. The wiring of high-speed signal lines should be very careful, because high rates exceeding 5Gbps have entered the microwave field. The distortion caused by channel discontinuity must be considered at such a high rate through connectors and cables. In order to maintain the degree of distortion at a controllable level, the cable needs to pass a series of test items such as impedance, delay, hysteresis, attenuation and crosstalk.
USB Type-C cable materials
can obtain different functions and performance by connecting to the USB Type-C interface and matching the corresponding E-Marker chip, but this is not enough. Because power, data and audio and video transmission ultimately need to be implemented on the data and power cores in the cable, and the materials used in the latter will directly determine the transmission quality of various signals.
For example, the really particular cables need to add steel sleeves and hard sealant to protect and insulate, and the wire body is covered with metal shielding nets and shielded aluminum foil to prevent signal interference. The cable flexibility is increased by filling Teflon insulators, Kevlar wires, tensile wires and cotton wires. The higher the cable diameter, the thicker it is, but after optimization through the above methods, it can significantly improve its bending resistance and effectively resist daily wear.
And some unqualified cables are either very thin and feel extremely poor in the touch, or they are particularly hard, and they are afraid of breaking them when bending and storing.
We might as well take a well-known data cable brand as an example and see its internal materials for its USB Type-C cables of different specifications. Taking a cable that supports 5A and USB2.0 data transmission as an example, it only requires 4 sets of wire cores inside, and uses an ordinary bold tin-plated copper core.
For cables that support 5A and 10Gbps data transmission and audio and video output, 10 tin-plated copper cores and 8 silver-plated copper cores are required to design. If it is a lightning wire that supports 40Gbps, the silver-plated copper core needs to be bolded.
cables that support audio and video output. In order to ensure the stability of the signal, most coaxial cable structure is required. Each wire includes an independent insulating protective sleeve layer, outer conductor shielding layer, insulating layer and inner conductor, etc. (Figure 21).
However, when the signal is transmitted in the coaxial cable, the attenuation it is subject to is related to the transmission distance and the frequency of the signal itself. For high-frequency signals, the longer the transmission distance, the greater the signal attenuation. Therefore, the length of the highest-end lightning wire generally does not exceed 0.5 meters. If it exceeds 0.5 meters, it requires an additional chip to amplify the signal, which is extremely costly.
Generally, the price of 0.5-meter lightning wire is mostly within 250 yuan, while the price of 2 meters is about 600 yuan. Moreover, when connecting to storage peripherals with non-thunderstorage protocols, the latter can only transmit data at USB2.0 speed.
USB Type-C cable source
Although the USB Type-C interface has taken over almost all electronic devices except the iPhone, the cable specifications that match it are also dazzling, because different types of products have high and low requirements for it. For example, the USB Type-C interface on the Bluetooth headset can be charged as long as 1A, and the mobile power supply that supports 65W PD fast charging only requires 3A.The USB Type-C interface on the mobile hard drive is only responsible for transmitting data. The low-priced cables on the market are actually prepared for the above-mentioned devices, and they are enough.
Relatively speaking, the USB Type-C interface on laptops and mobile phones has higher expectations for cables, but this also depends on the specific model.
Take laptops as an example. The USB Type-C interface on many mid- and low-end products only supports 5Gbps data transmission. Better ones support 10Gbps data transmission, and better ones also support PD protocol charging and DP video output functions in addition to data transmission. This type of USB Type-C is what we often call "full-functional type".
data-type USB Type-C interface can be used with pure USB Hub to expand more USB, network cable interface or card reader
full-function USB Type-C interface can be paired with high-end docking stations including HDMI and charging interface
In high-end notes themselves, we can also see the emperor-level Thunderbolt 3/4 interface. With the popularity of the 11th generation Core notebooks, the Thunderbolt interface has gradually declined to the mid-range market. Many 11th generation Core thin and light notebooks at a price of 4,000 yuan have been equipped with Thunderbolt 4 standard.
Thunderbolt interface can be paired with an external graphics card dock or a 5K~8K resolution monitor
In the mobile phone field, the USB Type-C interface on the product, represented by Huawei Mate/P series and Nut R2, both support video output, which is equivalent to a full-function type, and can also be paired with the dock dock in the picture above to output the screen to the monitor and operate with a keyboard and mouse. Unfortunately, the USB Type-C interface of more models in the mobile phone circle only supports 18W PD charging (excluding the private fast charging protocol) and USB2.0 data transmission capabilities.
From an economic perspective, we should match the cables with enough USB Type-C interface functions on the specific device at hand. But from a practical point of view, the author still recommends that you buy at least one full-function USB Type-C cable that supports 5A, 10Gbps and DP video (4K) output. The brand data cable is mostly priced between 60 and 80 yuan, which is the most cost-effective, and is enough to meet the needs of charging, data transmission and external displays for various electronic products at home. No matter what device is available, it will not affect performance.
As for the lightning cable, unless you want to connect an external monitor or external graphics card with a super 5K resolution, and the PC at home must also be equipped with this interface, otherwise there is no need to choose this type of emperor-level cable.
