Is USB current @ 3A safe to use?

[ahdai]

I plan to make a regulated 5v 3A max power supply and will attach 4 female USB bracket to it. I understand that the current draw will be determined by the load. In my case it will be my PDA and MP3 players.

I have not seen a USB power supply that high current like mine selling anywhere. Do you guys think it is safe for my USB gadgets?

 

[Mikebits]

Not a chance.
USB in a NutShell - Chapter 2 - Hardware
USB.org - Documents

 

[ParkingLotLust]

Mike, maybe he means he's going to build a USB charger - just a 5v supply connected to a few USB plugs, to charge things like MP3 Players and whatnot.

If he means that he's going to pull 3A from a USB port then youre right, there's no chance.

 

[ahdai]

The links you provided are talking about official USB specifications. The 500ma was fixed to protect the PCB and circuit on the motherboard from burning up.(thin copper lines and wires can't take the current)

If you do a simple search, there are tons of different adapters that offers 5v @ 1000ma. What i am trying to do is 3 times as much current.

Anyone else care to say something?

 

[ahdai]

Yes, i am making a USB charger that can offer up to 3A max. Just wondering if it will be safe?

 

[crutschow]

Yes, i am making a USB charger that can offer up to 3A max. Just wondering if it will be safe?

As long as you plug in USB devices that are designed to be powered by the USB port, I don't see a problem.

 

[Someone Electro]

Yeah 3A will power 4 devices without a problem. Because no device is allowed to draw more than 500mA.

 

[Mikebits]

Sorry, I misunderstood. I was thinking that you wanted to draw 3 amps from your USB.
So what you are saying is that you have a 3A supply and want to use it to power your USB devices. That should work with plenty to spare.

 

[Sceadwian]

Make sure you run heavy +VCC and GND wires to each connector, and preferably separate ones to each. Ideally you'd want to use separate +5 regulators to keep noise from transferring, but if these are just for charging and not for communication it's not needed, just make sure the regulator can handle +/- 1 amp current swings and still maintain regulation. You can always use large output capacitors to help buffer the regulator's input and output.

 

[ahdai]

Thanks everyone for the feedback. I have done it and my PDA charges damn fast now. Forgot to mention that it is powered by solar energy. Now i can charge every USB device i have without a PC.