By Ed Cady, Contributing Editor
USB 3.1 Type C is a new copper and optical cabling interconnect solution developed, released and supported by the USB-IF (Industry Forum) consortium. Type C USB connectors are getting a lot of attention because they are also being adopted by several AV standards like DisplayPort, HDMI, MHL and Thunderbolt. Talk about connectivity convergence! It is also being used for some 12G-SAS single link and 16G-PCIe 1-3 lane links applications. The current generation of Type C USB connectors supports 10G per lane data rate. It is a fourth generation, very small, nano-size connector; remember microUSB, miniUSB and the older giant standard Type A with power option?
It also eliminates the device equipment need for separate power cord assemblies as the Type C copper cable includes up to 100-W power wires within the cable jacket. The mated connectors are designed very carefully, achieving the proper level of power integrity and signaling integrity while keeping energy fields separate with optimized shielding and grounding features.
Next generation Type C USB connectors development is underway with the goal of achieving a minimum 20 G per data lane for TB-3; it may be further defined within a nascent USB 3.2 specification. Maybe this connector should be called Type D? Could this design be modified to achieve even higher performance and still backward? Some evangelists are endeavoring it to be useful for single link 24G-SAS, Ethernet 1x25G, IB 1x26G and other interfaces that would be cause to have a Type D connector.
If the 24-pin Type C connector had two more contacts, one each at the end of each row, it could be supporting some 4-lane I/O interface applications like SAS 4.0 4x12G = 48G multilink, PCIe 4.0 4x16G = 64G link, Ethernet 4x25G = 100G link or IB 4x 26G = 128G link. The two extra contacts would cause the connector to grow wider from 8.4 to 8.9 mm, which is smaller than the four lane OCuLink connector which is 13.45 mm wide. These two different connector types have contacts that are on 0.5 mm pitch bit while the OCuLink contact rows are staggered with 42 pins versus the 26 pins of a modified Type C. The current Type C 1-3 lane I/O connector may be competing in some applications versus the new 10G microSFP 1-3 lane connector, which is 11.35 mm wide with 22 contacts.
Type C cable plug paddleboard space is very small although a stick module implementation would have a long PCB for memory chips. For an active copper or active optical cable plug, paddleboard can barely support the latest signal conditioning and optical engine’s chips. However, Murata semiconductor offers an optical engine module that is embedded with a Type C plug connector making the active optical cable assembly process much easier. You could embed a similar module on the inside of a box with an optical receptacle on the outboard size. So just external passive optical cables would connect to the box port. Need some help figuring that out?!
Think of the myriad cable adapters with different connectors on each end and all the large and small hydra, multi-legged cable assembly possibilities. One could use existing Type C components and double stack top over bottom, two PCB mirror mount receptacle connectors, and have one over-molded double plug or an all metal hard shell that can support 6x or 6 lane single cable assemblies. Some consumer cables will have ergonomic designs like the classic ceramic-like overmold Thunderbolt2 versus rectangular and circular plastic or metal clamshells cable end plug connectors for industrial automation and MIL applications.
Higher temperature polymer plastic housings are necessary for strength and other environmental requirements. Samsung indicates that its newest smartphone seen in TV/Internet ads is waterproofed to a user-friendly consumer level. Thus one would expect that its Type C receptacle connector port is also waterproof/tight and that there will be different types of waterproof cables, stick modules or port caps being coming available. Maybe some application specific or general product lines like Chrome tablets will also have waterproof products with new Type C ports and cables.
Be aware of interoperability and compliance issues with early supplier limited component and assembly types of Type C USB connectors. Read up on future plugfest testing results for more on this topic.