Hi,
Planning to connect an AM3358 USB Device port to a USB hub on the same PCB.
The USB hub is powered from the USB Connector 5V OR from the main 5V source.
The CPU is powered only from the main 5V.
A USB - Serial port is connected to the AM3358.UART0 and is used amongst other things to log
the behaviour of the AM3358 during power loss.
The AM3358 is not allowed to be powered by the USB 5V for this an other reasons.

During main 5V power loss, the USB hub is powered and will drive the USB downstream port to the CPU, but the CPU is not powered.
This WILL damage the CPU, according to TI.

Ideally, there would be a USB 2.0 hub which would enable the down stream port only when allowed so by an active high signal, which I guess would be connected to AM3358.VCCIO.

I have not found such a part.

Alternatively, there would be a part which would allow bidircetional communication on USB, but could be powered down, and could tolerate one of the ports beeing driven by the USB hub. There are such parts called redrivers, but I have yet to find a datasheet which explicitly allows the part to be powered down.

Anyone got a clue how to solve this problem?