USB 2.0 Voltage

Can somebody tell me what voltage a USB 2.0 port puts out, what the cable is capable of transferring and how much voltage an Ipod takes in? Thanks, kidboy

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LasVegas10 years ago
The voltage of USB 2.0 is the same as USB 1.1. It supplies 5v at 500mA.
kidboy (author)  LasVegas10 years ago
Why did I think it was 3.3 volts?
tchall kidboy5 years ago
3.3 volts, or 2.7 volts is what the CPU uses... regulated down from the power supply's 5V bus...

USB ports are supposed to deliver up to 1 amp but typically the desktops will share a 1 or 2 amp power supply among two or more ports...

Worse yet many laptops reduce that output to about 1/4 amp.

SOME phones (and my Motorola Droid are among them) won't charge from 5 volts... their chargers run between 5.5 and 5.7 v

Or I should have said they won't charge from shutdown voltage from a USB port... once they have a partial charge they can use a lower voltage to complete charging....
StarrS2 tchall1 year ago

My Kyocera won't charge on a laptop usb port. It will "maintain" but that's about it. Just not enough amperage at 500 MA. Maybe usb 3 will help us out.

westfw kidboy10 years ago
If your "device" needs a voltage more tightly regulated than "4.5 to 5.5V", 3.3V is the closest "standard" voltage to aim for without fancy voltage regulators. There's a good chance the iPod is 3.3V on most of its internal circuitry...
awahabgms4 years ago
how can we covert 12 volts into 5 volt,,,for usb current only and how to reduce the ampers also, thnx
Get a 7805 voltage regulator.
Can a 6V battery be used to 'charge' devices through the USB cable?

i.e. a sealed lead-acid 6V 4.5 Ahr battery like the ones used in emergency lighting - I am looking for a way to keep a USB camera 'alive' to take a long time-lapse picture sequence. Long in duration taking pictures for a several day period.

Thank you in advance - I am new to this Instructables web page :-) and like what I am seeing posted!
6V is too much. You will need to drop it down to 5V. Placing a protection diode between the battery and the camera should do the trick. Any diode that has a forward voltage of about 1V like the 1N400x series of diodes will be perfect.
Brennn1010 years ago
Just to add, all voltage from your computer is exactly 5 volts. That is why its important for home-brewed electronics to make sure you have 5 volts, or you will blow out your device you want to charge for example.
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