Micro USB Power cable -- which are the power pins

A micro USB power cable is just a micro USB cable that doesn't have the data line wires.

You can still plug it into into a computer (laptop, or otherwise), just to access the power.

You could also plug it into something like this

Sylvia.

You may find many devices are not capable of providing 700 mA. Common protective devices limit output power to 500 mA.

We power several of our gadgets through a micro-USB. We just buy a Samsung universal AC-to-USB brick for about $4, good to 700 mA. We recently added a 2 amp version to stock, to power some bigger stuff. Be careful... there are a lot of really bad, really cheap USB power supplies around.

Here's an example product:

You don't need to find the pinout, unless you want to wire to the plug. NO ONE wants to manually wire to a mini-USB plug; just buy a prewired cable/plug assembly (or, equivalently, sacrifice a cable or an unsatisfactory power adapter).

Just use your voltmeter on the unsatisfactory adapter's output wires to find the right polarity, before you cut the cable off.

lot

I see you ground all the signal lines.

Do you not need the USB connectivity or ignore just those lines ?

hamilton

ung

ed a 2

re a lot

The data lines are normally numbered 2 and 3, 4 is ID So I'm guessing most of the grounded pins are actually mechanical

If you don't need usb but just power I think the standard says you should short d+ and d- to signal that you want high current

-Lasse

lot

Right. We generally assign a pin number to all the mechanical pads, to remind us to ground them or not. That board gets power only, no USB communications. Other boards do real USB, generally through an FTDI serial chip.

Interesting. I wonder if the power supplies are smart enough to notice.

amsung

added a 2

e are a lot

mind us

Other

some of them probably are:

But I think most of what a chip like that does is signal to the device how much power it can expect, so say a tablet can charge at 2A when connected to a charger and at 500mA when connected to a computer

I guess you could use that, so if someone plugs your device into a computer that will only supply 500mA, you can tell him it won't work

-Lasse

That was the USB 1.0 standard. 2.0 was 1A

-Lasse

these protective devices aren't particularly common in the wild.

Samsung

added a 2

there are a lot

No need to guess. The standards are available here:

Nice price as well.

?-)