Confused about powered USB hubs

[Tackemon]

Got a MiSTer setup going a couple of weeks ago and have been having a blast.

Recently I moved from a passive USB hub to an active USB hub, and got an unexpected result. When I unplug the main DE10 power, the hub continues to power the DE10 and standard I/O board. Wha...? I know there's lots of information out there about using powered USB hubs, including a recent thread on this Newcomers Forum, but it seems the more I Google it and read about it, the more confused I am.

For now I'm leaving the powered hub unplugged (it acts as a passive hub) unless using the wifi dongle, since I only need wifi for SSH, FTP, and update_all.

What is the "proper" approach here? Am I in danger of damaging the DE10 from a powered hub?

[Sorgelig]

Use the same power supply for both de10-nano and USB hub. This is most appropriate way.
Cheap USB hubs may supply the power back to USB host if voltage is higher than from USB host. So it will back-power the de10-nano which is your case.
de10-nano's USB is OTG which means it can be a host and device, so when you turn off the power on de10-nano, it turned to a device powered from USB.

[aberu]

Use the same power supply for both de10-nano and USB hub. This is most appropriate way.
Cheap USB hubs may supply the power back to USB host if voltage is higher than from USB host. So it will back-power the de10-nano which is your case.
de10-nano's USB is OTG which means it can be a host and device, so when you turn off the power on de10-nano, it turned to a device powered from USB.

The DE10-Nano doesn't have a diode to restrict this kind of backflow?

[Sorgelig]

The DE10-Nano doesn't have a diode to restrict this kind of backflow?

Please read my explanation again. de10-nano doesn't need diode. It works as designed.

[Sorgelig]

update: it seems later revisions of de10-nano can't be powered from USB.

[ash2fpga]

Do you know if there is an easy way to check if it can be powered by USB? (e.g., serial # / board layout / component)

[movisman]

I did find this but it doesn't necessarily answer the question. The components listed on the doc only suggest flash memory / clock generator component changes.

https://www.terasic.com.tw/cgi-bin/page ... a46a338bf3

A
First Release

B
Change Partner Text on PCB

B2
Change EPCS128 to EPCS64

C
- Change Power components due to long lead time.
- Change the clock generator from U15 (CDCE937) to U35 (Si5350C).
- Change EPCS64 to IS25LP064A-JBLE (Compactable with EPCS64)

[Sorgelig]

Do you know if there is an easy way to check if it can be powered by USB? (e.g., serial # / board layout / component)

easiest way to check is connect MicroUSB plug from PC - if you see any lights on de10-nano then it's powered
I only tested A which can be powered and C which cannot.

[Tackemon]

I think I'm just going to leave the USB hub unpowered. I tried using the wifi dongle (the ASUS one) without the USB hub's power supply and was still able to FTP in, so apparently there's enough power for that, in spite of the warnings I've read. I'll just enable the wifi dongle as needed. Each port on the hub has an on/off switch, so that's easy enough.

Seems like the safest bet?

I forgot to mention that I am using an upgraded Mean Well 4A power supply for the DE10 (this one: https://www.amazon.com/gp/product/B01D0Z8PLW). I don't know if that has an impact on any of this.