USB Connector: Types, Speeds, and Compatible Versions Compared

A USB (Universal Serial Bus) connector, or a USB interface, is an electronic part that facilitates the connection between a computer and peripheral devices such as printers, scanners, keyboards, and mice. It is part of the USB applications, they are designed to support data transfer and power supply between devices, and they are known for their plug-and-play functionality, allowing users to connect devices without needing to restart the computer.

Types of USB Connectors

USB Types Descriptions

Up to now, there are many types of USB interfaces, as shown in the following:

1. USB Type-A

• The standard rectangular connector found on most computers and chargers.

• Commonly used for connecting peripherals like keyboards, mice, and flash drives.

2. USB Type-B

• Square-shaped connector typically used for printers and some external hard drives.

• Variants include USB Type-B Mini and Type-B Micro.

3. USB Type-C

• Reversible connector that can handle power, data, and video.

• Gaining popularity in laptops, smartphones, and other devices due to its versatility.

4. USB Mini

• Smaller than Type-B, often used in older portable devices like cameras and MP3 players.

5. USB Micro

• Smaller than Mini, widely used in smartphones and tablets.

• Variants include Micro-A and Micro-B, with Micro-B commonly used for charging and data transfer.

Although it is not a USB standard, the Lightning interface used by Apple devices is also a common charging and data transmission interface.

USB Classification by Size

Main Types	USB Type-A	USB Type-B	USB Type-C
Size	• Standard • Mini • Micro	• Standard • Mini • Micro	Only one size
Figure 2: Main Types of USB Connectors

USB Type-A

There are several types of USB Type-A, the most common is the standard type. Also there is a non-standard small Type-A USB port (basically eliminated):

• Mini Type-A

• Micro Type-A

• USB3.0 Micro Type-A

• USB 2.0 (4 metal contacts)

• USB 3.0 (9 metal contacts)

Figure 3: Standard Type-A USB Metal Contacts

Note: Although blue USB ports are generally USB 3.0, it is much more accurate to distinguish USB 2.0 and USB 3.0 by looking at the contacts rather than by color.

USB TYPE A 2.0 PINOUTS
Pin	Signal	Description
1	VBUS	+5V
2	D-	Data-
3	D+	Data+
4	GND	Ground

USB TYPE A 3.0 PINOUTS
Pin	Signal	Description
1	VBUS	+5V
2	D-	Data-
3	D+	Data+
4	GND	Ground
5	SSRX-	USB 3.0 signal receiving line
6	SSRX+	USB 3.0 signal receiving line
7	GND	Ground
8	SSTX-	USB 3.0 signal transmission line
9	SSTX+	USB 3.0 signal transmission line

The Type-A USB interface is a standard connector, which means it is widely recognized and supported across different manufacturers and devices because of several advantages:

1) Widespread Compatibility: It’s the most common USB connector, found on virtually all computers and many peripherals. What’s more, type-A USB is compatible with the serial port and supports hot plugging, and Intel does not charge patent fees.

2) Ease of Use: The rectangular shape is easy to insert and offers a straightforward design.

3) Established Standard: Type-A has been around since the inception of USB, ensuring robust support across devices.

4) Power Delivery: It can provide power to devices, making it versatile for charging and data transfer.

5) Affordable: Type-A connectors and cables are generally low-cost and readily available.

USB Type-B

There are several types of USB Type-B: 

• Standard Type-A
• Mini Type-B（2.0/3.0）
• Micro Type-B
• USB3.0 Micro Type-B

• USB 2.0 (4 metal contacts) 

• USB 3.0 (9 metal contacts), compatible with 2.0

Figure 4: Standard Type-B USB Metal Contacts

Commonly found on old devices, because it only has 5 metal contacts and only supports USB 2.0 (Mini B).

Figure 5: Mini USB Type-B on MP3

• Micro Type-B (2.0 Android port) 

• USB3.0 Micro Type-B

Figure 6: Micro USB Type-B

USB TYPE B PINOUTS
Pin	Signal	Description
1	VBUS	+5V
2	D-	Data-
3	D+	Data+
4	GND	Ground

Micro USB PINOUTS
Pin	Signal	Description
1	VBUS	+5V
2	D-	Data-
3	D+	Data+
4	ID	OTG USB
5	GND	Ground

Mini USB PINOUTS
Pin	Signal	Description
1	VBUS	+5V
2	D-	Data-
3	D+	Data+
4	ID	OTG USB
5	GND	Ground

USB Type-C/Type-C/USB C

USB Type-C is a versatile connector used for data transfer and charging. It features a reversible design, meaning you can plug it in either way, which adds convenience. USB-C supports various protocols, including USB 3.2, Thunderbolt 3, and DisplayPort, allowing it to handle high-speed data transfers and video output.

Figure 7: Powerful USB Type-C

USB Type-C has several notable features that set it apart from other USB connectors:

1) Reversible Design: The connector can be plugged in either way, eliminating the frustration of trying to insert it the wrong way.

2) High Data Transfer Speeds: Supports USB 3.1 and USB4 standards, enabling data transfer speeds up to 40 Gbps, depending on the version.

3) Power Delivery (PD): Capable of delivering up to 100 watts of power, allowing for faster charging of devices, including laptops.

4) Versatility: Can carry power, data, and video signals, making it suitable for various applications like connecting monitors and external storage.

5) Universal Compatibility: Designed to be a universal connector, it can replace many older connectors, streamlining device connections.

6) Enhanced Durability: Typically more robust than previous USB types, with a design that can withstand more insertion cycles.

7) Support for Alternate Modes: Allows for different protocols (like HDMI and DisplayPort) to run over the same USB Type-C connection, increasing flexibility.

8) Small Size: Compact design makes it ideal for slim and portable devices.

Figure 8: Apple's USB Type-C for iPhone

USB TYPE C PINOUTS
Pin	Signal	Description	Pin	Signal	Description
A1	GND	Ground	B1	GND	Ground
A2	SSTXP1	USB 3.0/3.1 signal transmission line, positive	B2	SSRXP1	USB 3.0/3.1 signal transmission line, positive
A3	SSTXN1	USB 3.0/3.1 signal transmission line, negative	B3	SSRXN1	USB 3.0/3.1 signal transmission line, negative
A4	VBUS	Bus power	B4	VBUS	Bus power
A5	CC1	Configuration channel	B5	SBU2	Sideband use
A6	DP1	D+	B6	DN2	D-
A7	DN1	D-	B7	DP2	D+
A8	SBU1	Sideband use	B8	CC2	Configuration channel
A9	VBUS	Bus power	B9	VBUS	Bus power
A10	SSRXN2	USB 3.0/3.1 signal receiving line, negative	B10	SSTXN2	USB 3.0/3.1 signal receiving line, negative
A11	SSRXP2	USB 3.0/3.1 signal receiving line, positive	B11	SSTXP2	USB 3.0/3.1 signal receiving line, positive
A12	GND	Ground	B12	GND	Ground

USB Versions

USB has gone through several versions, each improving upon the previous one in terms of speed, power delivery, and functionality. Here's a quick overview:

1. USB 1.0 and 1.1

• Introduced in the 1990s, offering speeds from 1.5 Mbps (Low-Speed) up to 12 Mbps (Full-Speed).

2. USB 2.0

• Released in 2000, supports speeds up to 480 Mbps (High-Speed).

• Widely used for a variety of devices.

3. USB 3.0

• Introduced in 2008, offers speeds up to 5 Gbps (often referred to as USB 3.1 Gen 1, SuperSpeed).

4. USB 3.1

• Released in 2013, supports speeds up to 10 Gbps (known as USB 3.1 Gen 2, SuperSpeed+).

• Improved power delivery and data transfer capabilities.

5. USB 3.2

• Introduced in 2017, with speeds up to 20 Gbps using dual-lane operation.

6. USB4

• Announced in 2019, capable of speeds up to 40 Gbps.

• Integrates Thunderbolt 3 compatibility and enhanced data management.

Figure 9: Comparison of Theoretical Transmission Speeds of Different USB Versions

Figure 10: Compatible Versions of Different USB Connectors

Each version generally maintains backward compatibility, meaning newer USB ports can work with older USB devices, although speeds will be limited to the older standard. And each version can be used with USB Type-C connectors, but not all USB-C ports support the same speeds or power delivery capabilities. It’s always good to check the specifications of your devices.

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