How do I provide external power to my industrial USB hub?
Industrial USB hubs offered by StarTech.com require an external power supply that connects to the terminal block on the hub.
To select a power supply, you need to determine the maximum power requirements (wattage) of the hub.
The equation you should use to determine the power requirements is P = 5 * I * N, where the following is true:
- P is the power in watts.
- 5 is the voltage of the USB port.
- I is the current of the USB port in Amps.
- I = 0.5 A for USB 2.0.
- I = 0.9 A for USB 3.0.
- N is the number of USB ports.
For example, a four-port USB 3.0 hub's maximum power requirement is P = 5 * 0.9 * 4. Therefore, the minimum wattage of the power supply for the four-port USB 3.0 hub is 18 watts.
When you determine the power requirements of the hub, you can choose a power supply. The following criteria must be met when you select the power supply:
- The voltage must be within 7 to 24 or 7 to 40 Volts DC, depending on the specifications of the USB hub.
- The power supply must convert AC to DC (no AC output).
- The power rating is equal or greater to the requirements of the hub.
Most power supplies come with a rating in volts (V) and amps (A). 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 (between 7 to 24 or 7 to 40 volts).
For example, if a hub requires 18 W and you choose a 12 V power supply, the current of the power supply would be I = 18/12, I = 1.5A.