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TUSB8020B: Powering the host and a downstream device through the second downstream device.

Part Number: TUSB8020B

Good afternoon,

I would like to use the TI's reference design TIDA‐00287 with TUSB8020B to connect one host and two downstream devices. The host will be a tablet. One of the down stream devices is a Sub GHz wireless module and the other down stream board must power both the tablet and the Sub GHz module. 

Is it principle possible? Can I simply modify the schematic and get the power from the designated downstream device? 



  • HI Amir,

    USB 2.0 / USB 3.0 specifications do not allow for downstream devices to backdrive VBUS into an application. In a closed system, however, VBUS can be handled in non-compliant ways, but it is up to the end user to implement that application.