Dear Fellow Mi Fans!
There are many queries why Mi 6 only support up to Q.C. 3.0 instead of Q.C. 4.0 (since Qualcomm SD 835 SoC support up to Q.C.4.0), well, nonetheless, Xiaomi's CEO (Mr. Lei Jun) officially revealed in his Weibo account (e.g. China's equivalent micro-blogging to Twitter), Mi 6 not only supports Q.C.3.0, it also supports USB Power Delivery (PD).
If you are wondering what is USB PD, let me share more of it here. First, let me re-cap the highlights of the Mi 6 specifications.
A simple charging test is conducted on the Mi 6, using different chargers, and a current & voltage meter is used to readout the charging voltage and current. In 3 different tests conducted, it is conclusive that the Mi 6 supports Q.C 3.0 & USB Power Display.
#1 . Using Xiaomi USB-C Charger
First test, the Xiaomi 65W USB PD charger (#CDQ-2QM) is used and using the Power-Z current & voltage meter, it displayed 'USB PD' and the charging watts is 9.05V ×1.76A＝15.5W.
#2 . Using ROMOSS Power CUBE-EX
Second test, a ROMOSS Power CUBE-Ex (#AC30U) charger is used, the Power-Z current & voltage meter also displayed 'USB PD'，and the charging watts is 9.36V ×1.68A＝15.4W.
#3 . Using ZMI #10 POWER BANK
In the last test, the ZMI #10 power bank (#QB820) is usee, and Power-Z current & voltage meter also displayed 'USB PD'，and the charging watts is 8.77V ×1.86A＝16.3W.
USB, short for Universal Serial Bus, is an industry standard that defines cables, connectors and communications protocols for connection, communication, and power supply between computers and electronic devices. It was designed to standardize the connection of computer peripherals (including keyboards, pointing devices, digital cameras, printers, portable media players, disk drives and network adapters) to personal computers, both to communicate and to supply electric power. It has largely replaced a variety of earlier interfaces, such as serial ports and parallel ports, as well as separate power chargers for portable devices - and has become commonplace on a wide range of devices. Initially developed in the mid-1990s, it is currently developed by the USB Implementers Forum (USB IF).
In general, there are three basic formats of USB connectors:
There are 5 modes of USB data transfer, in order of increasing bandwidth:
All the 5 modes have differing hardware and cabling requirements. USB devices have some choice of implemented modes, and USB version is not a reliable statement of implemented modes. Modes are identified by their names and icons, and the specifications suggests that plugs and receptacles be colour-coded (SuperSpeed is identified by blue).
Unlike other data buses (e.g., Ethernet, HDMI), USB connections are directed, with both upstream and downstream ports emanating from a single host. This applies to electrical power, with only downstream facing ports providing power; this topology was chosen to easily prevent electrical overloads and damaged equipment.
Thus, USB cables have different ends: A and B, with different physical connectors for each. Therefore, in general, each different format requires four different connectors: a plug and receptacle for each of the A and B ends. USB cables have the plugs, and the corresponding receptacles are on the computers or electronic devices. In common practice, the A end is usually the standard format, and the B side varies over standard, mini, and micro.
The mini and micro formats also provide for USB On-The-Go (OTG) with a hermaphroditic AB receptacle, which accepts either an A or a B plug. On-the-Go allows USB between peers without discarding the directed topology by choosing the host at connection time; it also allows one receptacle to perform double duty in space-constrained applications.
There are cables with A plugs on both ends, which may be valid if the cable includes, for example, a USB host-to-host transfer device with 2 ports, but they could also be non-standard and erroneous.
# USB 1.x
Released in January 1996, USB 1.0 specified a data rate of 1.5 Mbit/s (Low Bandwidth or Low Speed). It did not allow for extension cables or pass-through monitors, due to timing and power limitations. Few USB devices made it to the market until USB 1.1 was released in August 1998, which introduced the speed of 12 Mbit/s (fast speed). USB 1.1 was the earliest revision that was widely adopted and led to what Microsoft designated the "Legacy-free PC".
Neither USB 1.0 nor 1.1 specified a design for any connector smaller than the standard type A or type B. Though many designs for a miniaturised type B connector appeared on many peripheral devices, conformance to the USB 1.x standard was fudged by treating peripherals that had miniature connectors as though they had a tethered connection (that is: no plug or socket at the peripheral end). There was no known miniature type A connector until USB 2.0 (rev 1.01)
# USB 2.0
USB 2.0 was released in April 2000, adding a higher maximum signaling rate of 480 Mbit/s (High Speed or High Bandwidth), in addition to the USB 1.x Full Speed signaling rate of 12 Mbit/s. Due to bus access constraints, the effective throughput of the High Speed signaling rate is limited to 280 Mbit/s or 35 MB/s.
# USB 3.0
The USB 3.0 specification was released on 12 November 2008, with its management transferring from USB 3.0 Promoter Group to the USB Implementers Forum (USB-IF), and announced on 17 November 2008 at the SuperSpeed USB Developers Conference. It defines a new SuperSpeed transfer mode, with associated new backward compatible plugs, receptacles, and cables. SuperSpeed plugs and receptacles are identified with a distinct logo and blue inserts in standard format receptacles.
The new SuperSpeed mode provides a data signaling rate of 5.0 Gbit/s. However, due to the overhead incurred by 8b/10b encoding, the payload throughput is actually 4 Gbit/s, and the specification considers it reasonable to achieve only around 3.2 Gbit/s (0.4 GB/s or 400 MB/s). However, this should increase with future hardware advances. Communication is full-duplex in SuperSpeed transfer mode; earlier modes are half-duplex, arbitrated by the host.
Low-power and high-power devices remain operational with this standard, but devices using SuperSpeed can take advantage of increased available current of between 150 mA and 900 mA, respectively. Additionally, there is a Battery Charging Specification (Version 1.2 – December 2010), which increases the power handling capability to 1.5 A but does not allow concurrent data transmission.The Battery Charging Specification requires that the physical ports themselves be capable of handling 5 A of current but limits the maximum current drawn to 1.5 A.
A January 2013 press release, from the USB group revealed plans to update USB 3.0 to 10 Gbit/s.The group ended up creating a new USB specification, USB 3.1, which was released on 31 July 2013, replacing the USB 3.0 standard.
# USB 3.1
The USB 3.1 specification takes over the existing USB 3.0's SuperSpeed USB transfer rate, also referred to as USB 3.1 Gen 1, and introduces a faster transfer rate called SuperSpeed USB 10 Gbps, also referred to as USB 3.1 Gen 2, putting it on par with a single first-generation Thunderbolt channel.
The new mode's logo features a caption stylized as SUPERSPEED+. The USB 3.1 Gen 2 standard increases the data signaling rate to 10 Gbit/s, double that of SuperSpeed USB, and reduces line encoding overhead to just 3% by changing the encoding scheme to 128b/132b. The first USB 3.1 Gen 2 implementation demonstrated transfer speeds of 7.2 Gbit/s, whereas the USB 3.1 standard is backward compatible with USB 3.0 and USB 2.0.
USB has evolved from a data interface capable of supplying limited power to a primary provider of power with a data interface. Today many devices charge or get their power from USB ports contained in laptops, cars, aircraft or even wall sockets. USB has become a ubiquitous power socket for many small devices such as cell phones, MP3 players and other hand-held devices. Users need USB to fulfil their requirements not only in terms of data but also to provide power to, or charge, their devices simply, often without the need to load a driver, in order to carry out “traditional” USB functions.
The USB Power Delivery Specification enables the maximum functionality of USB by providing more flexible power delivery along with data over a single cable. Its aim is to operate with and build on the existing USB ecosystem.
USB Power Delivery offers the following features:
Power Delivery is designed to co-exist with standard USB Battery Charging implementations. Implementers should note that if they include battery charging capability in their devices or support for host adapters such as docks or ACAs they should also reference the Battery Charging Specification.
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