USB interface growth process

The USB specification is constantly updated, and there are significant changes from the communication rate to the interface form. As can be seen from the table below, the communication rate has increased exponentially. The fastest theoretical data communication rate currently available is USB4 and Thunderbolt interface compatible up to 40Gbit / s.  The interface form is also from few to many, and finally to one of Type-C, which meets the current needs of people for high-speed communication and large charging

1 USB 1.X era

In the USB 1.0 period, most devices did not reserve a USB port, and the operating system support was not enough. The concept of USB files was too abstract, which made the popularization of USB technology very difficult.  During the USB 1.1 period, the USB communication rate increased, and the Windows 98 operating system built-in USB interface module, USB was generally favored by peripheral manufacturers.

2 USB 2.X era

In August 2000, the USB 2.0 standard was officially announced.  In the USB 2.0 specification, the most important thing is to increase the higher data transmission rate of 480 Mbps, which belongs to half-duplex communication and is still widely used.

USB 2.0 has brought it into a glorious period. On the host side, almost all personal computers support USB. On the device side, devices using the USB interface are increasing, such as digital cameras, scanners, printers, mice, and keyboards.  Its biggest advantage lies in "hot swap", "portability", "uniform standard", "can connect multiple devices", and gradually eliminated the parallel port and other old interfaces of PC.

During the USB 2.0 period, a supplementary USB protocol was added, OTG (On-The-Go), and the USB interface added an ID pin, which was used as the basis for the judgment of the host and slave.  OTG is mainly used for connection between various devices or mobile devices for data exchange, such as PAD, mobile phones, consumer devices, etc. without host communication.

3 USB3.X era

USB3.0 is a new-generation USB interface. It is characterized by a very fast transfer rate, which can theoretically reach 5Gbps, surpassing IEEE 1394 and eSATA in a comprehensive way, adding more parallel physical buses, and achieving full-duplex communication.

After USB3.1, the Type-C interface is basically used, and the communication rate is also multiplied. The 24 definable pins of Type-C far exceed USB-A and USB-B.

4 USB4.X future era

The USB-IF Alliance has released the protocol standard of USB4.0. According to the protocol standard, the maximum rate of USB4.0 can reach 40Gbps, and the USB-C interface (specific pin functions are still being developed). At that time, the USB interface can support PCIE.  Device, then USB interface can be directly connected to the graphics card to experience ultra-high-definition video.

The most anticipated change of the USB update interface-PD charging

In the USB 2.0 era, it can provide 5V@500mA=2.5W of power, and the Battery Charging working group of the USB-IF Association began to promote the use of USB / miniUSB / microUSB cable as the charging specification for mobile device battery power supply.  Including the Battery Charging (BC) v1.0 specification in 2007 and the BC v1.1 specification in 2009; after the introduction of the USB 3.0 specification in 2008, it can provide 5V@900mA=4.5W of power, although USB 3.0 provides 5V / 0.9A  power supply.  But people still hope for a stronger power supply capability, so USB 3.1 (SuperSpeed +) has increased the maximum allowable standard of power supply to 20V / 5A, power supply 100W.

Whether it is 2.5W of USB 2.0, 4.5W of USB 3.0 or 7.5W of BC 1.2, these charging / power supply specifications that used to accompany the USB bus in the past, although they can meet the charging requirements such as mobile phones and MP3, but often need to consume a lot  It takes time to fully charge; even at the BC 1.2 specification, with only 7.5W of charging power, it takes between ten to several hours to charge a general smartphone. For larger tablets and even laptop devices,  Charging / power supply is impossible.

So USB-IF set up another Power Delivery (Power Delivery) working group to embark on the ambition of using USB bus to provide more power charging / supply current.  In July 2012, the USB Power Delivery (PD) 1.0 specification was first announced, through five power supply setting levels (Profile 1 to 5), up to 100 watts of power transmission, as well as the power supply terminal (Source) and power receiving terminal  (Sink) The bidirectional power supply feature can be mutually oriented, so that various devices can meet the power supply needs through a single USB cable, shorten the device charging time and optimize the convenience of mobile applications.  At the same time, it is compatible with the existing USB 3.0 / 2.0, BC 1.2 / 1.1 / 1.0 charging specifications.

Detailed explanation of USB Power Delivery technology and architecture

USB Power Delivery (USB PD) has formulated the most basic Profile 1 (providing 5V @ 2A, 10W power supply for portable devices such as mobile phones and digital cameras) and Profile 2 (providing 5V @ 2A,  12V@1.5A, 10 ～ 18W power supply, suitable for tablet computers, external storage devices), Profile 3 (provide 5V @ 2A, 12V @ 3A, 10 ~ 36W power supply, suitable for Ultrabook, deformable tablet and other devices), Profile 4 (  Provide 5V @ 2A, 12 / 20V @ 3A, 10 ～ 60W power supply, which is the maximum power supply specification supported by microUSB, suitable for general high-performance notebooks, AIO computers), and the highest level Profile 5 (provide 5V @ 2A, 12  / 20V @ 5A, 10 ～ 100W power supply, used for standard A / B and Type-C connector, can be connected to LCD display,