USB hubs, multi-port splitters
This text is machine translated.
About USB hubs and interface distributors
USB is the standard interface for current computers. Almost every peripheral device – from the USB stick to the printer – occupies a USB port. But what was to be done when all connections on the computer were occupied? It's clear that a USB hub must be her.
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Overview of USB hubs and interface distributors
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Current standards
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USB On-The-Go
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Active and passive USB splitter
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The different USB connector types
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What was to be considered when purchasing USB hubs and interface distributors?
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Our practical tip: USB hub with integrated SD card reader for traveling
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FAQ - Frequently Asked Questions about USB Hubs and Interface Distribution
Overview of USB hubs and interface distributors
You probably know the problem: Quickly connect a mouse, a memory stick, the smartphone and then perhaps the printer to the notebook – and all USB ports are occupied. A USB splitter is an uncomplicated and economical solution to increase the number of connection options. The useful distributors are available as small and compact hubs, which usually offer four to five ports, fit easily in the bag and are thus always with you while traveling. For stationary operation at the desk there are significantly larger models with 10 or more ports. Some versions offer individually switchable on and off ports. This can be useful for completely disabling unused devices and also for saving power. Many devices have an LED indicator to indicate which ports are currently active. In addition, hubs can be equipped with other useful functions, such as an integrated Ethernet adapter or a reader for SD cards.
USB hubs can be designed as devices with housings or as plug-in cards or front slots for installation in the computer. In addition, not only distributors for USB but also hubs for the serial interface RS232 are available. This is still used today by various devices, such as UPS systems or barcode scanners. Furthermore, there are distributors for FireWire or DisplayPort.
Current standards
The specification for the USB standard was already adopted in 1998. Since the old standards USB 1.0 and 1.1 no longer play a role today, we start directly with USB 2.0. The interface provides a gross data rate of up to 480 MBit/s, of which approximately 40 MByte/s net remains. The maximum current is 0.5 A and the maximum power is 2.5 Watt. A look at the specifications shows that USB 2.0 is not suitable for storing large files due to the rather slow speed.
With the successor USB 3.0, the gross data rate was increased to 5 GBit/s (about 450 MB/s net). The current here is 0.9 A and the maximum power is 4.5 watts. The USB 3.1 Gen 1 extension does not change the transmission speed; when using the USB-C connector, the maximum current can increase to 3 A and the power to 15 watts. The increased performance is especially useful when charging external devices. A further significant increase in speed was possible with USB 3.1 Gen 2. The gross data transfer rate has doubled to 10 Gbps compared to Gen 1. Net of this, about 800 MByte/s remain. Current strength and maximum power remain unchanged.
The current iteration of the USB standard is the version USB 3.2 (as of 2019). In this case, too, the gross data rate is doubled compared to 3.1 Gen 2. This is now 20 GBit/s, was approximately 2 GByte/s net. With USB 3.2, the USB-C plug is used for the first time without exception. Current and power remain at the level of 3.1 Gen 2 and thus are at a maximum of 3 A and 15 Watt. The next major development step of the interface will be USB 4. A gross data rate of 40 GBit/s is to be expected here.
USB On-The-Go
A USB device is usually connected to a computer. It serves as a host and provides drivers and, if necessary, necessary software to be able to recognize the connected device. Direct communication between two USB devices is not possible in this way. With USB On-The-Go, or OTG, there is the option that a USB device can serve as a host in a certain framework. For example, a camera could send images to a printer without having to go through the computer. However, this only works if both devices are OTG compatible.
Active and passive USB splitter
Connected devices such as a mouse or a memory stick are supplied with power directly via the USB port. However, all ports on a hub share the voltage provided by the computer through the cable. Since the hub is usually only connected to one USB port at a time, only the energy supplied by the hub is available for the hub. With USB 3.0, for example, this would be 0.9 A and 4.5 watts, which the hub must distribute to all its ports. If all ports on such a passive distributor are used, a connected device may not function. In this case, the power supply is simply no longer sufficient. This issue can be addressed with an active hub. These devices have a separate power supply, which ensures that the full power is available at each individual available connection. In this way, distribution boards with 10 or more connections can be used, without having to accept loss of performance when using multiple or full connections.
The different USB connector types
The USB standard provides for different plug types, which are replaced by the type C plug from USB 3.2 on. The rectangular type A connector is the most common form and is used with most devices that are to be operated on a computer. The range of devices ranges from input devices to external hard disks to printers and scanners.
Cables with a Type B connector are typically used to connect peripheral devices such as printers to the computer. Since there is hardly a computer with a type B socket, such printer connection cables usually have a type A plug on the other side. Mini USB plugs are significantly smaller than the Type A plugs and are mainly used in cameras, MP3 players and other smaller devices. In this case, too, the corresponding cables often have a type A connector on the opposite side, which enables a connection to a PC. The micro USB plug fails even a smaller number. It is still used in many mobile phones. Cables with micro USB plugs are also equipped with type A plugs for connection to the computer or to a USB charger.
What was to be considered when purchasing USB hubs and interface distributors?
As so often, when purchasing a USB hub, the question of the purpose of use is decisive. Do you travel a lot? Then you should choose a compact distributor without additional power supply. Four to five ports should be sufficient for most cases. For a hub, which is to be used primarily at home at the desk or in the office, however, you should preferably fall back on an active model with additional power supply. Consider how many ports you need before you buy. The more ports a hub offers, the more expensive it is usually. It is recommended not to buy a USB 2.0 hub, but instead to buy a modern 3.0 model. By the way, you don't have to worry about compatibility: A USB 3.0 device works as usual on a USB 2.0 interface and vice versa. However, a 3.0 hard drive connected to a 2.0 port only works at the maximum speed of 2.0.
Our practical tip: USB hub with integrated SD card reader for traveling
If you're on the go, it's a good idea to get a compact and rugged USB hub with a durable aluminum housing. Some USB distributors are equipped with an integrated SD card reader and thus save you the need to take another device with you.
FAQ - Frequently Asked Questions about USB Hubs and Interface Distribution
What was USB-C?
This is not a transmission standard such as USB 3.0. USB-C only defines the plug, which can be connected via Thunderbolt or USB 3.2, for example. If Thunderbolt works in the background, USB-C can also transfer DisplayPort, audio signals or PCI Express.
What was the benefit of USB-C?
The plug has the advantage that it is very small and the ports on the computer can be correspondingly compact. This allows notebooks to be made even thinner, as the manufacturer Apple has demonstrated with its devices. Moreover, the plug is absolutely twist-proof and can therefore be easily inserted even in the dark, which was quite practical with smartphones. USB-C also represents a major step forward in terms of power supply: The standard itself is designed to deliver up to 100 watts of power. This means that not only small devices such as MP3 players or mobile phones can be charged via USB, but also notebooks. If the Thunderbolt protocol is behind the type C plug, it is possible to either charge a notebook, connect a compatible monitor or extend the computer with an external graphics card with only one socket.
My USB hub has a connector next to which there is a battery icon. What is the purpose of this?
This is a so-called quick-charge connection that you can use to charge your smartphone or tablet. Compared to the other ports on the hub, the charge port provides a significantly higher current, which enables fast charging with compatible devices.