Powering a board with USB

Hello,

You can't get 1A from a USB2.0 nor USB3.0 downstream port, what you can do is to modify the hardware of your Host board (the one that is providing the VBUS to your board) and make it not to monitor the current draw of the USB port, that way the power switch providing the VBUS will not be limited by the USB controller.

Below picture show a typical USB implementation, chances are that your board that provides VBUS is configured that way, you will have to disconnect the "control" and the "current sense" lines in the below picture to do what I mentioned above.

The other option is to use an external power supply in your board.

Regards

Hi Elias,

That makes sense, but aren't there devices on the board receiving the power that perform the negotiation to tell the board delivering the power how much power to deliver? Basically, what device is used to perform the negotiations on the board receiving power?

Best,
Jared

The USB device will tel to the Host controller how much power it needs, however the max current for a USB3.0 is 900mA, so there is no way to get 1A.
The above solution is to prevent the USB controller to shut the device down when more current is drawn, the USB device will still be telling to the Controller to require 900mA, however you will be able to draw more current with an external power source when the USB controller is not in charge of the current draw monitoring.
The implementation will be non-compliant with USB but you will still be able to draw 1A.
Regards

Hi Elias,

Right, so you mentioned the "USB Device" will tell the host controller how much power it needs.. can you please provide an IC part number for this USB device?

thank you,
Jared