Difference Between USB 2.0 and 3.0

Fast data transfer has always been a serious task with the digital geeks. USB interface has been playing a vital role in this case. USB 2.0 and USB 3.0 do have their own achievements in this competition. In this article we are going to discuss both of them comparatively and will figureout the difference between usb 2.0 and 3.0. Before the comparison, first we are going to give a general overview of each of them. 

difference of usb 2.0 vs 3.0

USB 2.0 Specifications:

The USB 2.0 has specifically been designed to transfer data communication as fast as 480 Mbps. Despite upgrading, USB 2.0 is fully compatible with USB 1.x. Normally, USB 2.0 operates at the rate of 12/1.5 Mbps when it is connected to a full/low-speed device.

The port may operate at the speed of 480 Mbps when connected to a high-speed. The following are the internal key features of USB 2.0. 

KEYUSB2.0 (HS Capability)
Signal400mV Differential 480Mbps
IdleSE0 (D + = D – Low)
SYNC32 (12 min) symbols
EOP“0” + 7 “1” (39″1″ for SOF)
ConnectFS->HS
DisconnectVoltage level of SOF EOP
ResetLong SE0 with chirp
TransactionSOF, Setup, In, Out, Ping, Split
Control64 byte
Bulk512byte
Interrupt1 – 1024 byte (1024 × 3 MAX )
Iso.1 – 1024 byte (1024 × 3 MAX )
Get Desc.Dev., Config., Qualifier, Other

USB 3.0 Specifications:

As obvious by it’s number, USB 3.0 is a modified version of USB 2.0 and as such, is more efficient than its predecessor. The data transmission speed of USB 3.0 reaches 5 Gbit/s which is almost ten times faster than its predecessor whose speed was 0.48 Gbit/s. Besides, apart from the speed factor, USB 3.0 is fully duplex where its predecessor was just half duplex. 

KeyUSB 3.0 (HS Capability)
Signal 500 MB/s  5 Gbit/s
Fast IdleLink is idle (when it is in low state) with the transmit/receive specs temporarily being inactive. Signal latency is pretty low so it can exit fast. But, the term is applicable for SuperSeed only
SyncIn case the data is halted at the endpoint, there is a “STALL” message. In case of a less buffer zone space/data, the response will be Not Ready (NRDY) signal. The said signal will intimate its incapability to process the request.

What is the Difference Between USB 2.0 and 3.0?

There is a logical question as to what is the difference between usb 2.0 and 3.0 when we compare the two. The major difference is that the USB 2.0 comes with a data transfer rate of 480 Mbps while USB 3.0 offers a data transfer rate of 4.8 Gbps which means 10 times faster transfer rate. Besides, the data transfer speed depends on the following features as well. 

  • Device in use
  • The bus type
  • USB ports
  • Cables 

The following table compares and contrasts the specs and features of the two products. The effort has been made to make the difference stand out.

Bus TypeMax Transfer RateUSB 3.0 Transfer SpeedUSB 2.0 Transfer Speed
PCIe 1.0a2.5 Gbps2.5 Gbps480 Mbps
PCIe 2.0/2.15 Gbps4.8 Gbps480 Mbps
PCIe 3.08 Gbps4.8 Gbps480 Mbps
ExpressCard 1.02.5 Gbps2.5 Gbps480 Mbps
ExpressCard 2.05 Gbps4.8 Gbps480 Mbps

difference between usb 2.0 and 3.0

The addition of another physical bus is also a countable difference. The addition of another bus doubles the amount of wires that is, from 4 to 8. The additional wires, however, need extra space in components like cables and connectors. This led to introduction of new connectors for both B Male and Micro B Male connectors. The size of these connectors are large enough to accommodate the additional wires and as such, they are not compatible with USB 2.0 ports. 

Also, the available power and power management features of the USB 3.0 products gives it edge over USB 2.0. Previously, USB 2.0 offered only up to 500 mA while the new modified USB 3.0 offered three times more power option that is, up to 900 mA. This feature let the devices work much faster than before. Besides, the technology used in USB 3.0 is very efficient in power consumption. For example, it removes power completely off when the device is not in use.

How are USB 2.0 and USB 3.0 Different in Terms Of Cables?

Before attempting to answer the asked question, let it be clear as to what difference there if the number of cables increases. The answer is pretty simple, the more number of cables, the faster data transfer possible. Now the answer to the asked question is that the USB 2.0 with 4 cables enabled only at 480 Mbps with a power supply up to 500 mA while the USB 3.0 with 8 cables made the data transfer possible at 4.8 Gbps with the power option of 900 mA. Thus, doubling the number of cables expedited the data transfer very much faster. 

Besides the number of cables, they are also different in terms of connectors. The USB 3.0 comes with different types of connectors. They are normally in blue color on the inside contrasted with its counterpart that come in white/silver plastic color. As a matter of observation, the modified versions of every device happen to be different not only in terms of efficiency but also in terms of compatibility. So the older versions are not compatible with the modern, advanced versions and so is true of USB 2.0. Simply, it means the USBs using different connectors can’t use the connectors USB 2.0 uses. But if you try to fit 2.0 connectors into 3.0 ports, the difference in configuration chocks the data flow. It’s only A connectors that work with 2.0 devices along with a 2.0 cable that can fit into 3.0 ports/hubs and still work efficiently. 

Is a USB 3.0 Compatible with USB 2.0 devices?

Yes, of course. As said earlier the advanced versions support their predecessors and so is the case with the USB 3.0 and USB 2.0 which means 3.0 support 2.0. But, the limitations will be there. The 3.0 connected with 2.0 device will allow data transfer rates and power options same as 2.0 and not as 3.0.

How To Tell The Difference Between USB 2.0 and USB 3.0 cables?

The following two features can help you identify if the USB is 2.0 or 3.0. The USB 2.0 cables include four pins whereas the USB 3.0 include nine pins. Also, 3.0 comes with a larger “B” (device) end. The larger end means it’s not going to fit into 2.0 devices such as scanners, printers etc. Also, the 3.0 cables often have blue color inside. Also, they have prominent “SS” that is, (SuperSpeed) which is mentioned next to the device logo.

How To Tell A USB 3.0 Port from USB 2.0?

The USB 3.0 on a PC can be easily identified by having a look on its Device Manager. Besides, if the physical ports are blue or carry a “SS” (SuperSeed) logo, it means it’s a USB 3.0.

What Is The Application of USB 2.0 and/or 3.0?

Primarily, both of the USBs are used for data transfer or when the question is of bandwidth and so are they applied in devices. For example, if there are high bandwidth devices that need a maximum bandwidth of 480 such as mass storage devices like video adapters, data transfer cables etc, you can opt for USB 2.0 Hi-Speed. On the other hand, if there are high bandwidth devices that require a maximum bandwidth of 4.8Gbps such as large storage devices like video adapters, data transfer cables etc, you better head for USB 3.0 Super-Speed.

Hopefully, you got a thorough knowledge about the USB 2.0 and USB 3.0. on the “compare and contrast” style discussion and now you are able to use them accordingly. 

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