Hi,
I want to buy a portable MP3 player (not IPod), but it requires a
"high power" USB port on a computer to charge it. The alternative is to spend
around $30.00 for a "wall wart" type of charger.

I am a service technician, and I thought about using one of my regulated
power supplies. You can set voltage and current. Also I have the USB
connector (same type computer has), but I don't know what current
I should set to charge the MP3 player. I realize that may depend on the MP3
player, but I am looking for a nominal value as a reference.

Do you have information on the typical charging current?

Thank You in Advance, John

PS, Remove "ine" from my email address

On Tue, 23 Feb 2010 07:42:34 -0500, wrote:

Hi,
I want to buy a portable MP3 player (not IPod), but it requires a
"high power" USB port on a computer to charge it. The alternative is to spend
around $30.00 for a "wall wart" type of charger.

I am a service technician, and I thought about using one of my regulated
power supplies. You can set voltage and current. Also I have the USB
connector (same type computer has), but I don't know what current
I should set to charge the MP3 player. I realize that may depend on the MP3
player, but I am looking for a nominal value as a reference.

Do you have information on the typical charging current?

Thank You in Advance, John

PS, Remove "ine" from my email address


The USB specification is for a maximum of 500ma from a port to a
device that can send a highpower request. Otherwise, the limit is
less (180ma?).
However, the player will charge on less current; it just takes longer.

If you plan to charge the player overnight, then a 100ma source is
probably adequate.

Otherwise, set your bench supply for 5 volts and set the current limit
to 500ma and let it charge.

John

Hi!

I want to buy a portable MP3 player (not IPod), but it requires
a "high power" USB port on a computer to charge it.

"High power" is an Apple-esque description of a USB port that is part
of a *powered* USB hub or built in to a computer (a "root port").

Basically, as long as you plug the MP3 player into a USB hub with its
own power supply or directly into the computer, it will be fine.

If you were to plug it into a "passive" hub such as that found in a
monitor or keyboard with USB ports, there might be a problem with
insufficient power being available.

I am a service technician, and I thought about using one of my
regulated power supplies. *You can set voltage and current.

Be very aware of polarity, and make sure the power supply's regulation
is as good as you think it is, especially with light loads. The
designers of your MP3 player may have assumed that its power input
would never be mistakenly reversed or set to a voltage that was just
too high.

You are looking for 5 volts DC at a maximum of 500mA.

William