I'm looking for a USB C hub for my new iPad Air (something with HDMI and a regular USB port), but I'd also like to use pass through charging.
My concern is this: will a non-Apple usb-c hub potentially damage my iPad when I use pass through charging? Is there a list of approved usb-c hubs?
iPad Pro (5th generation)
Recent models of iPad employ USB PD (Power Delivery) over USB-C. Many USB-C hubs also support USB PD - allowing the Power Adapter to work properly in negotiating a mutually supported Power Profile for the iPad and Hub.
Providing that you choose a USB-C hub that has specifications that explicitly state compatibility with iPad - and you use a sufficiently powerful USB-C Power Adapter that supports USB PD, no harm will come to the iPad or connected devices.
You should note that not all USB-C Power Adapters support USB PD - but may use different proprietary charging standards.
In more detail…
Apple’s current range of Power Adapter’s, including those intended for Mac computers, support USB PD (Power Delivery). USB PD is an active protocol; the source (Power Adapter) and sink/load (in this case, your iPad) “negotiate” and agree a common Power Profile that will determine the charging voltage that will be applied.
For non-PD compliant devices - or compliant devices that fail to negotiate a mutually supported Power Profile - the Power Adapter will only supply the standard USB 5V at a reduced current. This mechanism ensures that the higher charging voltages not supported by non-PD devices are not damaged by an over-voltage condition.
You should note that while your iPad Pro can be safely charged with Power Adapters exceeding 20W, it will not charge any faster than when using the USB-C 20W Power Adapter that was likely supplied with your iPad. When charged with a USB-PD Power Adapter, the maximum iPad charging rate is limited to ~20W. When using a standard USB Power Adapter, operating at 5V, the maximum charging rate is limited to 12W (i.e., 2.4A @5V).
Where the higher-power Power Adapter does provide benefit is when being used with other USB devices via a USB hub. A higher-output Power Adapter provides a greater “power budget” - allowing other devices to receive power while maintaining the iPad’s maximum 20W charging rate. For example, a USB multiport hub may typically require 10W power; connected USB devices (external storage, keyboard, mouse etc) also draw additional power from the source. If the connected load exceeds the available supply, the iPad may not charge - or may charge at a substantially slower rate. In extremis, both the iPad and Power Adapter will share the connected load - and the iPad may actually discharge its battery to make-up the shortfall in available power from a connected Power Adapter.
You should note that while Apple devices generally support USB PD, they do not support other charging standards - such as QC (Quick Charge).
Recent models of iPad employ USB PD (Power Delivery) over USB-C. Many USB-C hubs also support USB PD - allowing the Power Adapter to work properly in negotiating a mutually supported Power Profile for the iPad and Hub.
Providing that you choose a USB-C hub that has specifications that explicitly state compatibility with iPad - and you use a sufficiently powerful USB-C Power Adapter that supports USB PD, no harm will come to the iPad or connected devices.
You should note that not all USB-C Power Adapters support USB PD - but may use different proprietary charging standards.
In more detail…
Apple’s current range of Power Adapter’s, including those intended for Mac computers, support USB PD (Power Delivery). USB PD is an active protocol; the source (Power Adapter) and sink/load (in this case, your iPad) “negotiate” and agree a common Power Profile that will determine the charging voltage that will be applied.
For non-PD compliant devices - or compliant devices that fail to negotiate a mutually supported Power Profile - the Power Adapter will only supply the standard USB 5V at a reduced current. This mechanism ensures that the higher charging voltages not supported by non-PD devices are not damaged by an over-voltage condition.
You should note that while your iPad Pro can be safely charged with Power Adapters exceeding 20W, it will not charge any faster than when using the USB-C 20W Power Adapter that was likely supplied with your iPad. When charged with a USB-PD Power Adapter, the maximum iPad charging rate is limited to ~20W. When using a standard USB Power Adapter, operating at 5V, the maximum charging rate is limited to 12W (i.e., 2.4A @5V).
Where the higher-power Power Adapter does provide benefit is when being used with other USB devices via a USB hub. A higher-output Power Adapter provides a greater “power budget” - allowing other devices to receive power while maintaining the iPad’s maximum 20W charging rate. For example, a USB multiport hub may typically require 10W power; connected USB devices (external storage, keyboard, mouse etc) also draw additional power from the source. If the connected load exceeds the available supply, the iPad may not charge - or may charge at a substantially slower rate. In extremis, both the iPad and Power Adapter will share the connected load - and the iPad may actually discharge its battery to make-up the shortfall in available power from a connected Power Adapter.
You should note that while Apple devices generally support USB PD, they do not support other charging standards - such as QC (Quick Charge).
iPaid Air (5th Generation) USB Hub and pass through charging ... will it damage?
