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General discussion • Re: RPI USB3 Hub question

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The input power is my one disappointment with the hub. USB 3 spec calls for 900mA per port. Unless one finds a PSU that will deliver more that 3A at 5v without using PD, the power input for the hub will be limited to 3A, which is an average of 750mA per port. So you could get the full rated USB 3 power, only if you limit the downstream to 3 of 4 ports. Personally, I think the RPT missed a bet (even at an increase in price) of not putting a PD "handshake" into the hub to allow it to accept the full 5A from a Pi5 PSU. Perhaps a future iteration will fix this.
There are powered hubs of up to 100Watts. Power is from a laptop type power supply but they can output lots of power on lots of ports.
But they aren't really in a Raspberry Pi sort of price range.

Regard a PD handshake in the hub, is there an hub IC that does this ? Might be the issue.
If the PMIC on a Pi5 can do it, there should be something even less complex that just does the PD handshake and accepts as much current as the PSU can deliver. Given what was done with the Pi4, it might be doable with a few simple components, though a chip that jsut does the handshake might be cheaper...or, at least, cheaper to integrate onto the PCB.

Statistics: Posted by W. H. Heydt — Wed Jan 29, 2025 12:05 am



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