USB host maximum current


I looked and I couldn’t find any information about how much current the E1 mkii can deliver via the USB host port.

I saw that the E1 itself peaks out at about 500mA. Does this figure include some theoretical margin for the current draw on the USB host port? Is it only for powering the E1 itself?

Assuming that the power supply used to power the E1 mkii can keep up, what is the maximum current that can be delivered via the USB host port?

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I can’t tell you the specs of E1, but know that in general USB2.0 is to be limited to 500mA at anytime over one single USB line.
In case you want to feed multiple USB instruments, totalling more than 500MA of current, ensure you use a powered USB hub

The 500mA current limit of the USB 2.0 ports on a computer motherboard is a good starting point but it doesn’t really help me because I am not using one.

I am powering my E1 (well, going to once it arrives) with a powered USB hub that can deliver 1.1 amps on each port simultaneously.

It would be nice to know when I would need a second powered USB hub when connecting devices to the E1 and when I can just plug them in directly/use a non-powered hub.

If the power rails of the USB host port are just simply connected to the power rails of the USB device port then the total available current on the host port would be the total available current of the power supply minus the current draw of the E1.

The power rails are connected. E1 mkII needs around 300mA. The PCB planes will handle 1.1A no problem.

Good to know!

I am planning on connecting two Blokas Miduhubs via a USB hub.

They draw 300mA each. I’m looking at a total consumption of about 900mA with about 200mA of headroom.