Mass USB charging

After looking at the datasheet for a very common Chinese USB hub controller chip (Genesys GL852) it seems that each port might be limited to a maximum of 100mA. This is presumably why your 35 port hub was only provided with a 4A PSU? You should be able to power it safely with a PC PSU if your hub is using this controller but you presumably won't be able to draw much more than 100mA per port.
http://www.genesyslogic.com/manage/upfile/11860396491.pdf
Texas Instruments controller datasheet
http://www.ti.com/lit/ds/symlink/tusb2046b.pdf

It's going to cost quite a bit to purchase a suitable number of hubs which can supply 500mA per port so you might need to do something different.
 
Last edited:
Yotch said:
After looking at the datasheet for a very common Chinese USB hub controller chip (Genesys GL852) it seems that each port is limited to a maximum of 100mA. This is presumably why your 35 port hub was only provided with a 4A PSU? You should be able to power it safely with a PC PSU if your hub is using this controller but you won't be able to draw much more than 100mA per port.
http://www.genesyslogic.com/manage/upfile/11860396491.pdf
Texas Instruments controller datasheet
http://www.ti.com/lit/ds/symlink/tusb2046b.pdf

It's going to cost quite a bit to purchase a suitable number of hubs which can supply 500mA per port so you might need to do something different.
Click to expand...

That is strange as I managed to charge about eight tablets using this hub, they must have been drawing 500mA on each port to charge right?



Sent from my HTC Desire using Tapatalk 2 Beta-5
 
If they were drawing only 100mA they would probably still charge but very slowly. Like a trickle charger
 
Decotey said:
If they were drawing only 100mA they would probably still charge but very slowly. Like a trickle charger
Click to expand...

Then the 5V 4A power supply shouldn't have a problem with trickle charging 34 tablets at 100mA each yet it melted with 17 on :P

Sent from my HTC Desire using Tapatalk 2 Beta-5
 
Well that's 3.4A your pulling off 4A rated.

It's probably not 4A rated for very long. Or 4A is the max theoretical that the power supply can produce.

*Oops didn't read only 17 on never mind.

But i suppose its possible that the power supply will get very hot at 1.7A
 
Last edited:
If you have an old ATX PSU lying around you could try to use it to power the hub via an IDE molex connector but only connect a few devices and test thoroughly before slowly increasing the number of devices. The current output of each port is supposed to be limited so I don't think that you will damage it. I doubt that it would be a good idea to draw 17A from one device though. I see that there are a number of 10 port hubs on Bidorbuy which seem to only be supplied with a 1~2A power supply which is why I think the output might be limited to 100mA per port otherwise it won't be difficult to overload the supply.
 
Cloud said:
Then the 5V 4A power supply shouldn't have a problem with trickle charging 34 tablets at 100mA each yet it melted with 17 on :P
Click to expand...
Broadly speaking and horribly over-simplifying voltage gets set by the power supply but current gets demanded, which is where you problem comes in: those devices you're charging en-masse aren't restricting to trickle charging, they're sucking all they're rated to for full charging, likely until they reach the point at which they sit on trickle charge.

Which, as you've found, melts that (for the job) weeny PSU.
 
USB is normally 100mA but a device may pull up to 500mA is what I understand for a normal computer.
Maybe the hubs are also limited to 500mA
 
bdt said:
Zaps have this Vantec 10-porter that comes with what may be a brick rated for the ports is has, which would get you out of the brick-melt zone. But you'd have to ask what it's rated at, it's not given anywhere (easily) findable.
Click to expand...

That is the golden question though, since most usb hubs are underpowered for charging on all ports.

Sent from my HTC Desire using Tapatalk 2 Beta-5
 
Budza said:
Why is this still being discussed?

Just get the damn multiplugs and 2prong adaptors!
Click to expand...

There are power considerations too, usb hubs take less power surely. Those black box power supplies are pumping all the time aren't they?

Sent from my HTC Desire using Tapatalk 2 Beta-5
 
Cloud said:
There are power considerations too, usb hubs take less power surely. Those black box power supplies are pumping all the time aren't they?
Click to expand...
Again, current is an on-demand thing. So, while those wee power bricks WILL be using %some_amount% of power, it would be for their own internal circuitry only. Which, with nothing drawing on them amounts to something pretty much too trivial to work out.
 
Cloud said:
There are power considerations too, usb hubs take less power surely. Those black box power supplies are pumping all the time aren't they?

Sent from my HTC Desire using Tapatalk 2 Beta-5
Click to expand...

Slightly more expensive multiplugs have switches per plug. Still probably going to be cheaper and easier than some complex multi port powered hub arrangement.

You're looking for excuses to run a fancy hub :)

Simpler is better. Just use the multiplug ;)
 
Budza said:
Slightly more expensive multiplugs have switches per plug. Still probably going to be cheaper and easier than some complex multi port powered hub arrangement.

You're looking for excuses to run a fancy hub :)

Simpler is better. Just use the multiplug ;)
Click to expand...

dude I have been saying that since the beginning :D

it will be simpler, possibly cheaper and more effective :/
 
You must log in or register to reply here.
Back
Top
Sign up to the MyBroadband newsletter
X