What Is the Difference Between Self-Powered and Bus-Powered USB Devices?

Self-powered USB device - A device that takes all of its power from an external power supply

Bus-powered USB device - A device that takes all of its power from the host computer's USB interface.

Why High-Current Devices Require External Power

While all USB ports provide some amount of power for attached devices, the available power may not be enough for certain high-current devices such as USB hubs or external hard drives. Bus-powered devices can cause issues if they need more power than is available from the host machine, as each additional device attached to the host computer reduces the total available bus power. If the power runs out, any USB device attached to the computer may suddenly disconnect, which could result in permanent data loss for a USB storage device.

How to Use Devices with Included Power Adapters

Many devices that include power adapters, especially USB hubs, will function in either self-powered or bus-powered mode. If a device comes with a power adapter, it should stay connected at all times, otherwise the device may not function as designed.

Applicable To

USBC-11IN1E, USBC-10IN1E, USBC-9IN1E, USBC-7IN1E, USBC-7IN1, AD-6IN1, USBC-4IN1, USB3-HUB4A, USBC-HUB4A, AMS-5IN1E, USB4-HUB3A, TBT4-HUB3C, USBC-HUB7BC, USB3-HUB7C, USB3-HUB3ME

Unfortunately Plugable products do not support the Apple SuperDrive.

The Apple SuperDrive has stringent power requirements that can only be met by directly connecting the SuperDrive to your host laptop. As a result at this time Apple recommends only using their USB-C adapter cables. You can find more information on that here → How to connect the Apple USB SuperDrive

If you have purchased a Plugable product to use with your Apple SuperDrive, and would like some additional assistance please do not hesitate to reach out. You can do so by emailing support@plugable.com, or going to Plugable.com/Support.

It's not uncommon for users to notice a certain level of heat generation from electronics and by extension, Plugable products during operation. In this knowledge base article, we'll explore the reasons behind this heat generation and why it is considered a normal experience within reasonable limits.

Electronics, by their nature, generate heat during operation. This is primarily a result of the electrical current flowing through various components, such as integrated circuits, transistors, and other electronic elements. As Plugable products are designed to efficiently process and transfer data (among other functionality), some level of heat generation is inherent.

Factors Influencing Heat Generation:

1. Power Consumption: The power consumption of a device directly influences the amount of heat it generates. Higher power usage, especially during data transfer or charging processes, can lead to increased heat.
2. Enclosure Design: The design of the product's enclosure and its ability to dissipate heat play a crucial role. Adequate ventilation and heat sinks are often incorporated to manage and disperse generated heat effectively. This is evident in our TBT3-UDZ and TBT4-UDZ designs. The metal case in these docks are designed to function as a heatsink with thermal pads placed throughout the enclosure. This allows heat dissipation from inside to the outside, but will also make it feel as if the device is “too hot”. 
3. Ambient Temperature: The external environment may also play a role. Higher ambient temperatures can contribute to increased perceived heat from the product. This means that summer temperatures may increase the heat generation of not just Plugable products, but many other electronic devices.

Normal Heat Levels: While it is normal for electronic devices to generate heat, Plugable products are engineered to operate within safe temperature ranges. We conduct rigorous testing to ensure that the heat generated during normal operation falls within industry-standard safety parameters. While not all products are or need to be UL certified, we try to go by UL guidelines for thermal readings. The UL threshold is 77C/170.6F, and we aim for around 71C/160F.

Tips for Users:

1. Ventilation: Ensure that Plugable products have sufficient ventilation around them. Avoid placing them in enclosed spaces where heat dissipation may be impeded.
2. Usage Patterns: Intensive tasks such as high-speed data transfer or charging multiple devices simultaneously may result in increased heat generation. This is generally normal but may be more noticeable in such scenarios.
3. Accessories: A number of our devices will allow for the connection of USB accessories and as such, these will require power. If too many “power-hungry” devices are connected, this will cause the device to run much hotter than expected. Be sure to keep in mind the power limits of your dock/device.

In conclusion, experiencing heat from Plugable products is a normal aspect of their operation. Users can rest assured that we prioritize the safety and efficiency of our devices. By understanding the factors influencing heat generation and following simple usage guidelines, users can make the most of their Plugable products while ensuring a reliable and efficient user experience.

Many users assume that USB-C devices can work with older Thunderbolt 2 Macs if they use a Thunderbolt 3 to Thunderbolt 2 adapter, such as the one made by Apple. However, this is not the case. These adapters are specifically designed to support Thunderbolt devices only - not standard USB-C peripherals.

While Thunderbolt 3 and USB-C share the same connector type, they use different underlying data protocols. Non-Thunderbolt USB-C devices, rely on USB standards for data and power. The Thunderbolt 3 to Thunderbolt 2 adapter does not carry USB signals; it only passes Thunderbolt data. Because of this, plugging a USB-C device into a Thunderbolt 2 Mac using this adapter will not work - the computer will not detect or communicate with the device.

If you need to connect peripherals to a Thunderbolt 2 system, we recommend using a USB-A dock or hub (if available on your system). This ensures compatibility without relying on unsupported adapter chains.

In short, even though the connectors may fit, USB-C devices are not compatible with Thunderbolt 2 Macs via Thunderbolt adapters - only Thunderbolt devices will work in that setup.

Improved Voltage Regulation Under Load

When multiple USB devices are connected - especially high-draw peripherals like external drives or charging phones - the demand on the dock’s internal power can spike. If the power supply were delivering only 5V, any load increase might cause voltage “sag,” potentially leading to unstable or unreliable performance.

By starting with a higher voltage like 12V or 20V, the internal voltage regulators within the dock or hub can more reliably and efficiently step down that voltage to a consistent 5V, even under heavy load. It’s similar to having a reservoir above a village - you’ll have more reliable water pressure regardless of demand.

Greater Power Efficiency Over Distance

Transmitting power at higher voltage and lower current reduces energy loss due to resistance in the wires (which causes heat). By increasing the voltage we can decrease the amperage for the same power, and power loss in the line is directly proportional to amperage squared so even a small decrease in the amperage adds up quickly. Once the power reaches the dock, it's stepped down to the voltages needed for USB ports. This not only enhances efficiency but also makes compact, cooler-running designs possible.

Special Consideration for USB-C Docks

USB-C docks commonly include 20V power supplies, which serve a dual purpose:

• Supplying 5V for downstream USB devices
• Delivering up to 100W (or more) to host laptops via USB-C Power Delivery

With USB Power Delivery 3.1 (EPR), even higher voltages (up to 48V) are supported, enabling future docks and laptops to handle even more powerful devices like desktop replacement laptops or external GPUs.

Will Future Docks Use 48V Power Supplies?

It's likely. While 20V is common now (especially for consumer devices), 24V+ power supplies are widespread in industrial and telecom applications. As high-performance laptops and workstations demand more power, consumer docks may start including 24V, 36V, or even 48V adapters. These would align with USB PD 3.1 specs and simplify designs that support extended power ranges.

However, for now, 20V remains a sweet spot for cost, availability, and compatibility across a wide range of devices.

TL;DR

Higher voltages like 12V or 20V are used for better regulation and more efficient power delivery.

USB-C docks use 20V to support Power Delivery charging (up to 100W+).

USB PD 3.1 EPR opens the door to 48V systems, and while uncommon now, future docking stations may shift to 48V as demand grows.

No, the USBC-2PORT is not compatible with vehicle USB ports.

Why the USBC-2PORT Cannot Be Used in Vehicle USB Ports

In-car entertainment systems (including those running Apple CarPlay and Android Auto) require a direct, one-to-one data connection between the vehicle and the device. They lack the capability to read USB hubs or splitters. If you plug a splitter into your car's USB port, the car's system will likely fail to recognize any attached devices.

Applicable To

• USBC-2PORT
• Modern computers, laptops, phones, and tablets running standard operating systems like Windows, macOS, ChromeOS, Android, or Linux

The USBC-2PORT is a USB 2.0 hub, meaning it supports data transfer speeds of up to 480 Mbps. It is highly recommended for "legacy" or low-bandwidth peripherals, including wireless mouse and keyboard receivers, wired keyboards and mice, and standard USB flash drives (thumb drives).

Why High-Bandwidth Devices Are Not Recommended

Because USB 2.0 has a bandwidth limit of 480 Mbps, using this splitter with high-bandwidth devices is not recommended. You may experience latency, dropouts, or failure to connect when using 4K or high-resolution webcams, external NVMe SSDs for heavy file transfers, or USB display adapters.

Applicable To

• USBC-2PORT