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tschmidt
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join:2000-11-12
Milford, NH
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reply to Edrick

Re: "Professional" Grade or High End USB Power

USB has the notion of a unit load. Early this was 100/500ma, USB 3 increased it to 150/900 ma at 5 Volts. The purpose of having two levels is the device must power up at low value and then request permission to switch to higher consumption. All upstream ports must be able to supply at least low power on a per port basis with high power being optional. This is what makes USB powered and unpowered hubs feasible and guarantees the bus will not become overloaded.

There is a special option for charging ports, that operate as power transfer only, no data transfer. They are limited to 1.5A, the upper limit of the connector.

There is a higher voltage option, kind of like Ethernet PoE, I don't know status or how well it has been received.

That is why you are not going to see 5V 2A USB per port capability. Are you sure any of the devices you have draw more then 900 ma or 1.5A? If so I'd be surprised.

/tom



Edrick
I aspire to tell the story of a lifetime
Premium
join:2004-09-11
Woburn, MA

If no device can accept over 1.5A then how come so many chargers tout 2.1A for one port?



tschmidt
Premium,MVM
join:2000-11-12
Milford, NH
kudos:9
Reviews:
·G4 Communications
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said by Edrick:

If no device can accept over 1.5A then how come so many chargers tout 2.1A for one port?

I have no idea.

/tom

robbin
Premium,MVM
join:2000-09-21
Leander, TX
kudos:1
reply to Edrick

said by Edrick:

If no device can accept over 1.5A then how come so many chargers tout 2.1A for one port?

One word -- iPad


cwnorris

join:2000-01-17
Longmont, CO
reply to tschmidt

Click for full size
My Asus tablet charger uses USB, but you need to have a USB 3.0 cable for it to charge at the higher rate.

»www.usb.org/developers/powerdelivery/


LazMan
Premium
join:2003-03-26
canada

1 recommendation

reply to Edrick

said by Edrick:

If no device can accept over 1.5A then how come so many chargers tout 2.1A for one port?

The -STANDARD- says no more then 1.5A - however, there are several devices (iPad probably being the most common) that are non-standard, and draw more....