External power is supplied by connecting to the terminal block located on the hub. For when an external power adapter is required, our 12V7A2P-B power supply is compatible and suggested.
To determine the power requirements, the equation to use is P = 5 * I * N, where:
P is the power wattage.
5 is the USB port voltage.
I is the current of the USB port in Amps (USB 2.0 is 0.5A, USB 3.0 is 0.9A.
N is the number of USB ports.
As an example using the equation, a 4 port hub would reflect a minimum wattage of 18 watts.
Knowing the minimum requirement, a proper power adapter can be chosen. In this case the voltage of a power supply should be within 7 to 24 or 7 to 40 Volts DC, depending on the specifications of the USB hub. Also, the power supply must convert AC to DC (no AC output).
Power supplies often come with a voltage (V) rating and an amperage (A) rating. To determine the current in amps, use I = P / V, where the following is true:
I is the current of the power supply.
P is the calculated power of the hub.
V is the chosen voltage of the power supply
Continuing the example, the 4 port hub requires 18 W and the power supply you choose is 12V, the current of the power supply would be I = 18/12, I = 1.5A.
Our full collection of power adapters can be found here.