Micro USB Power cable -- which are the power pins

If this is a slightly off topic query, I apologize. Could some electronics guru please help ? I am not at all familiar with the micro USB power cable, and here are some questions:

  1. As I understand it, the USB cable has a micro USB connector on one end, and a regular USB connector on the other. The power is fed in via the regular USB connector, and the micro USB connector plugs into the device that uses it. So, where do I connect the regular USB connector to, for the device at the other end to receive power over the USB cable. In my case, the receiving device needs a power supply that can supply 700 mA (max) at 5V. I can easily build a power supply to these specifications, and so could I just put a matching connector at the regular USB connector end of the cable, and then power the device this way. Please let me know your thoughts on this.
Reply to
dakupoto
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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

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Sylvia.

Reply to
Sylvia Else

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

Reply to
Richard Henry

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...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Reply to
Jim Thompson

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:

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John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    
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Reply to
John Larkin

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.

Reply to
whit3rd

lot

I see you ground all the signal lines.

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

hamilton

Reply to
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

Reply to
langwadt

2

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.

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John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    
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Reply to
John Larkin

amsung

added a 2

e are a lot

mind us

Other

some of them probably are:

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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

Reply to
langwadt

That was the USB 1.0 standard. 2.0 was 1A

Reply to
Michael A. Terrell

n
2.0 is also 500mA, 3.0 that is up to 900mA when running high speed, something like 1500mA when it is for charging

-Lasse

Reply to
langwadt

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

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Reply to
Jasen Betts

Samsung

added a 2

there are a lot

No need to guess. The standards are available here:

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Nice price as well.

?-)

Reply to
josephkk

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