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Tips for Buying USB-C Cables

manager Dec 20, 2017

     USB-C, technically known as USB Type-C, is the interface specification developed at roughly the same time as the USB 3.1 specification in August 2014. USB 3.1 has a top speed of 10Gbps and can deliver power up to 100 watts (20 volts and 5 amps). Today Type-C has been widely adopted and used in high-end phones and tablets to fulfill the advanced features of the USB 3.1. Greater performance means higher challenge. The high current over the Type-C cable demands high quality materials and components, and superior manufacture techniques.

  Cheaply-made low quality Type-C cables are dangerous and can permanently damage your devices. For this reason, we prepare this article to help you understand what a decent USB Type-C cable should be, and enjoy the USB 3.1 benefits for free.

What’s Type-C & What’s new

    USB-C, technically known as USB Type-C, is a 24-pin USB connector system, which is distinguished by its rotationally-symmetrical connector.

    USB standards have a long history, and they've gone through plenty of changes since first implemented in 1996. USB-C is the emerging standard for charging and transferring data. It is the first USB specification allowing reversible plug orientation, and able to charge your laptops and phones faster, transfer data more quickly and even send 4K video to your monitors.

    Type-C also revolutionizes the USB world by making many of the connector types we use today obsolete. With Type-C, audio, video, power and data can be all transferred over one connector. It’s no wonder new mobile devices and laptops are choosing to become slimmer at the expense of losing bulky legacy ports. Apple’s Thunderbolt 3 connector uses USB-C and Intel claims it has developed a USB audio standard to make the 3.5mm audio jack totally obsolete.

Greater performance means Higher challenge!

     The USB Power Delivery Specification revision 2.0 (USB PD rev. 2) has been released as part of the USB 3.1 suite. It covers the Type-C cable and connector, and permits uniformly charging laptops, tablets, USB-powered disks and similar higher-power consumer electronics. In some power profiles of the specification, the Type-C cable may carry up to 5A current (at 20 V) to charge a 100 W device. The high current over the cable demands high quality materials and components, and superior manufacture techniques. Some low-quality Type-C cables may not work properly, and even bring fire.

     Higher current requires a thicker wire to reduce electricity resistance. AWG (American wire gauge), also known as Brown & Sharpe wire gauge, defines the relationship of copper wire diameter and its current-carrying capacity.

      Below is an abstracted table of AWG wire sizes from Wiki, showing various wire gauges and the allowable current (ampacity). The smaller the AWG, the thicker the diameter, the smaller the resistance, and the higher the current the wire can carry. Inside Type-C cable, there are 2 types of wire, for data transmission and power transportation purpose. The copper wire size for power should be 20 to 28AWG, and the counterpart for data transmission should be 26 to 34AWG.

Abstracted table of AWG wire sizes

Source from Wikipedia

Type-A to Type-C cable

         One frequent usage scenario of Type-C cable is to provide power for USB 3.1 devices from USB 2.0 (massive in the market) hosts. Say, a USB Type-C to Type-A cable is delivering power to a phone from a computer. If the phone is set for charging at 3 amps (Type-C power specification) and the computer can only output 1.5 amps (USB Battery Charging 1.0 specification), the phone will try to draw more power than the computer can handle and may damage the computer USB port. To solve this issue, a 56kΩ pullup resistor is mandated in the specification for leveling power on the cable. Some non-compliant cables are missing this resistor or using 10kΩ instead, therefore fails to charge devices correctly and even may damage power sources such as chargers, hubs, or PC USB ports in the worst case.





How to buy a decent Type-C cable

Tip 1: Looking at the Plug!


        A high-quality cable uses a deep-draw extrusion method to produce the Type-C plug, which is a single piece of metal and has no visible seam on it. A folded and stamped connector as showed in the left picture, is usually made of zinc tin alloy, which is easily broken and may fail to handle the power over the cable.




Tip 2: Never buy a Type-C cable just because it's cheap!

       As mentioned above, Type-C has a stringent requirement on cables, and not all the cables are able to meet it. Cheap cables may have bad quality due to saving cost from thinner cooper wires, backward manufacture techniques as well as other tricks. In the worst case, those bad-quality cables may even permanently damage your expensive gadgets. It is important to make sure you buy a cable that’s trusted to do its job as it should.  

Tip 3: Choose a brand cable

     Quntis is a fast-growing eCommerce company focusing on USB Type-C cable products. Quntis has always committed to bringing more values to our customers by providing super high quality Type-C cables at a reasonable price.

     Today Quntis already serves millions of customers around the world. Our Type-C cables rank top sellers on Amazon with the honors like “Best Seller”, “Amazon’s Choice”, and “New Release” a dozen times. Combining our professional expertise and close partnership with global top OEM suppliers, we keep developing and expanding our product portfolio to bring you more convenience and more fun in the digital age.


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