USB hub - 5v? 12v?

[msacco]

Hello, another USB hub thread as I still didn't managed to find a clear cut answer to that.

I have a power USB hub which gets power from a micro USB cable and supports 5V@2A, it's a 4 ports hub and currently enough, but I want to build something and want to future proof myself with a 7 ports USB hub.
My question is whether I need a 5v hub or 12v hub. Currently my connected equipment is ZWO cooled camera, ZWO guide camera, mount connection and auto focuser, and it's connected without the micro USB power as so far it just worked fine with no issues.

Going with 7 ports, I probably won't be able to go without power, but will 5v@2A be enough for 7 ports? Obviously 12v@2A would allow much more power than 5v@2A, but I wonder if it's even needed?

Would love to know and understand more about this, thanks

[Davey-T]

No idea but I use a 7 port 12volt Startech hub with all sorts plugged in.

Dave

[Xplode]

It's better to go with a 12V usb hub because it's easier to power as you don't need an extra 5v power adaptor, but can instead use the same power supply as the mount, camera etc.
Most USB 2 hubs are 5v while most USB 3.0 hubs are 12v.

[msacco]

2 minutes ago, Xplode said:

It's better to go with a 12V usb hub because it's easier to power as you don't need an extra 5v power adaptor, but can instead use the same power supply as the mount, camera etc.
Most USB 2 hubs are 5v while most USB 3.0 hubs are 12v.

I actually already have a micro usb power cable, do it's not really an issue, and I know that most are 12v, but there are a few 5v ones.
I'm just wondering if it's actually needed though. I'll probably get 12v hub anyway to be on the safe side, but just want to better understand this

Thanks.

[Padraic M]

Like you, I'm looking to buy a single powered USB hub for all the mount-based equipment so that I can have a single USB 3.0 cable back to the laptop. It will need to support main camera, guide camera, filter wheel and the EQDIR connection to the mount itself. Possibly also a few other gadgets such as a focuser in time. The real high-current devices in astro are dew heaters, the mount motors, camera coolers and your laptop, none of which work on usb power.

ZWO ASI290mm mini guidecam is USB2.0 so max current (according to the usb spec) is 500mA.
ZWO EFW mini 5-port filter wheel 150ma max current @ 5V (from the ZWO website)
(e.g.) ZWO ASI1600mm Pro is USB 3.0 so max current is 900mA (usb spec). Cooling is powered by a separate 12V/3A power supply.
EQDIR connection to the mount is a usb-to-serial FTDI connection, and these are normally very low power (probably <50mA).

So total power requirement on the usb hub is up to 1.5A at 5V which is 7.5W. A 12V supply at 625mA would provide the same power. 

I'm not 100% sure that you can get powered usb hubs that take an external 5V power supply. All of the ones I've looked at are 12V. I suspect that the reason for this is that the designers of the powered hub would like to have a voltage regulator inside the hub, to provide a regulated 5V supply internally regardless of what a 'stupid user' plugs into that socket. At worst, you'll blow the hub if you supply overvoltage, and won't blow each of the devices you've plugged into it. Personally, I'd prefer to spend €50 on a new hub than ~€2,000 on two cameras, a filter wheel and a mount motherboard because I accidentally plugged my 12V supply into an unregulated 5V hub. Bear in mind that most 5V voltage regulators will actually handle an input voltage of up to 40V without burning up; but many will require an input voltage of 7V or higher (i.e. not 5V) in order to maintain a guaranteed 5V output. I wouldn't like to connect 40V to an ASI1600MM Pro!!!!

So in my view, it's not a power question (because you can supply any number of watts you want with different combinations of voltage and current) but of good design. 

Given that you say your device combination currently works fine without external power, then your max current requirement is relatively low. I can't say exactly what it is as some PCs will have high-power USB ports to support device charging (higher power than the usb spec mandates). The risk here is that if your device combination tries to draw more current than the usb port can provide, it may either a) shut down gracefully at its maximum power output, or b) burn out. It might be a good idea to go with external power anyway just in case (note to self: I don't!). Using my figures above, and to allow plenty of headroom for future expansion given that you're moving up to 7 ports, why don't you treble your current estimated power requirement of ~7.5W and spec your new hub at 20W, which is 12V@2.5A. Hopefully the internal regulator will efficiently convert that into 5V@4A. This will be total power to all ports simultaneously, and may allow any individual port draw down <3A.

Hope that helps!

Padraic.

 

[m.tweedy]

2 hours ago, Davey-T said:

No idea but I use a 7 port 12volt Startech hub with all sorts plugged in.

Dave

Ditto

[msacco]

1 hour ago, Padraic M said:

Like you, I'm looking to buy a single powered USB hub for all the mount-based equipment so that I can have a single USB 3.0 cable back to the laptop. It will need to support main camera, guide camera, filter wheel and the EQDIR connection to the mount itself. Possibly also a few other gadgets such as a focuser in time. The real high-current devices in astro are dew heaters, the mount motors, camera coolers and your laptop, none of which work on usb power.

ZWO ASI290mm mini guidecam is USB2.0 so max current (according to the usb spec) is 500mA.
ZWO EFW mini 5-port filter wheel 150ma max current @ 5V (from the ZWO website)
(e.g.) ZWO ASI1600mm Pro is USB 3.0 so max current is 900mA (usb spec). Cooling is powered by a separate 12V/3A power supply.
EQDIR connection to the mount is a usb-to-serial FTDI connection, and these are normally very low power (probably <50mA).

So total power requirement on the usb hub is up to 1.5A at 5V which is 7.5W. A 12V supply at 625mA would provide the same power. 

I'm not 100% sure that you can get powered usb hubs that take an external 5V power supply. All of the ones I've looked at are 12V. I suspect that the reason for this is that the designers of the powered hub would like to have a voltage regulator inside the hub, to provide a regulated 5V supply internally regardless of what a 'stupid user' plugs into that socket. At worst, you'll blow the hub if you supply overvoltage, and won't blow each of the devices you've plugged into it. Personally, I'd prefer to spend €50 on a new hub than ~€2,000 on two cameras, a filter wheel and a mount motherboard because I accidentally plugged my 12V supply into an unregulated 5V hub. Bear in mind that most 5V voltage regulators will actually handle an input voltage of up to 40V without burning up; but many will require an input voltage of 7V or higher (i.e. not 5V) in order to maintain a guaranteed 5V output. I wouldn't like to connect 40V to an ASI1600MM Pro!!!!

So in my view, it's not a power question (because you can supply any number of watts you want with different combinations of voltage and current) but of good design. 

Given that you say your device combination currently works fine without external power, then your max current requirement is relatively low. I can't say exactly what it is as some PCs will have high-power USB ports to support device charging (higher power than the usb spec mandates). The risk here is that if your device combination tries to draw more current than the usb port can provide, it may either a) shut down gracefully at its maximum power output, or b) burn out. It might be a good idea to go with external power anyway just in case (note to self: I don't!). Using my figures above, and to allow plenty of headroom for future expansion given that you're moving up to 7 ports, why don't you treble your current estimated power requirement of ~7.5W and spec your new hub at 20W, which is 12V@2.5A. Hopefully the internal regulator will efficiently convert that into 5V@4A. This will be total power to all ports simultaneously, and may allow any individual port draw down <3A.

Hope that helps!

Padraic.

 

Thanks for the comment, I totally agree with you. Isn't a 12v@2.5A gonna be 30W though? That should be plenty enough I think, it really isn't that costy either.

[Star101]

I've not heard of 5V powered hubs before. I know they can supply 5V, especially the Active Hubs powered by +12V power supply. Some have several USB3 ports and the end one or three sockets, with the 5V, is usually for charging iPhones etc. Such as this USB3 with charging ports

My USB 7 port active hub is fully utilized now. I have my rig and several USB drives connected to it. My plan is to move the 7 port USB onto my rig, so only the cameras/filterwheel etc are connected and next to my laptop have this beauty for all the USB Drives and anything else I wish to attache to it.

USB3 Powered hub

 

[Pompey Monkey]

1 hour ago, m.tweedy said:

Ditto

Me too.

It's worth paying a bit extra. Cheap USB  hubs have caused me all kinds of headaches over the years, and not just in astronomy. 

[Padraic M]

1 hour ago, msacco said:

Thanks for the comment, I totally agree with you. Isn't a 12v@2.5A gonna be 30W though? That should be plenty enough I think, it really isn't that costy either.

Indeed it is! Well spotted. Well worth having more power than you need as it can cause all kinds of hard-to-diagnose problems.

[Padraic M]

1 hour ago, Star101 said:

I've not heard of 5V powered hubs before. I know they can supply 5V, especially the Active Hubs powered by +12V power supply. Some have several USB3 ports and the end one or three sockets, with the 5V, is usually for charging iPhones etc. Such as this USB3 with charging ports

My USB 7 port active hub is fully utilized now. I have my rig and several USB drives connected to it. My plan is to move the 7 port USB onto my rig, so only the cameras/filterwheel etc are connected and next to my laptop have this beauty for all the USB Drives and anything else I wish to attache to it.

USB3 Powered hub

 

That's the one I'm looking at too.

[msacco]

Thanks for the comments guys, I've got myself a 12V@2A usb hub which a friend recommended me