usb power question

**perris** · January 30th, 2008

so I have a usb gps with a linux operating system, I have no idea which linux but I'll research to see if I can find out

anyway, it's powered from the cigarette lighter and I am wondering if the same power cord can be used with my pocket pc since that's usb charged also

does the os recognize voltage and adjust?

are the voltages common because of common processors?

thanx for the info in advance

**LeeJend** · January 31st, 2008

Usb standard dictates 5V voltage, voltage limits, power quality and maximum draw of 5W.

The pocket PC should not try and draw more than 5W so it should work. Skim thorugh the manual for the pocket PC and see if it says anything different.

The cigarette lighter plug adapter should specify it has a 5V, 5W output on the case. If it doesn't it may put out a higher voltage that could damage the pocket PC.

The GPS and Pocket PC manuals should specify what is expected on the power interfaces.

When all else fails. Can you plug either device into your dektop and recharge it? If yes, they both will work off of the USB standard.

Standards are great, unfortunately not everybody follows them...

Personally I would get a meter and measure the output from the USB charger with it plugged in if you can. Those pins are not real accessible. I fit reads under 6V with no load on it then you should be safe.

**perris** · January 31st, 2008

Originally Posted by LeeJend

Usb standard dictates 5V voltage, voltage limits, power quality and maximum draw of 5W.

The pocket PC should not try and draw more than 5W so it should work. Skim thorugh the manual for the pocket PC and see if it says anything different.

The cigarette lighter plug adapter should specify it has a 5V, 5W output on the case. If it doesn't it may put out a higher voltage that could damage the pocket PC.

The GPS and Pocket PC manuals should specify what is expected on the power interfaces.

When all else fails. Can you plug either device into your dektop and recharge it? If yes, they both will work off of the USB standard.

Standards are great, unfortunately not everybody follows them...

Personally I would get a meter and measure the output from the USB charger with it plugged in if you can. Those pins are not real accessible. I fit reads under 6V with no load on it then you should be safe.

thanx leejand, that answers the question perfectly, yes, both get charged from laptop

**Taurus** · January 31st, 2008

Originally Posted by LeeJend

Usb standard dictates 5V voltage, voltage limits, power quality and maximum draw of 5W.

i thought it was 500mA, so 2.5W..?

edit:

Originally Posted by wikipedia

The USB specification provides a 5 V (volts) supply on a single wire from which connected USB devices may draw power. The specification provides for no more than 5.25 V and no less than 4.75 V (5 V±5%) between the positive and negative bus power lines.[10] Initially, a device is only allowed to draw 100 mA. It may request more current from the upstream device in units of 2 mA up to a maximum of 500 mA.

January 30th, 2008	Top \| #1
perris OSNN Godlike Veteran Joined: January 2002 Location: new york Posts: 12,258 Reputation: 4333 Power: 291	usb power question so I have a usb gps with a linux operating system, I have no idea which linux but I'll research to see if I can find out anyway, it's powered from the cigarette lighter and I am wondering if the same power cord can be used with my pocket pc since that's usb charged also does the os recognize voltage and adjust? are the voltages common because of common processors? thanx for the info in advance IT'S NOT WHAT YOU'VE DONE IT'S WHAT YOU ARE GOING TO DO

January 31st, 2008	Top \| #2
LeeJend OSNN Veteran Addict Joined: January 2003 Location: Fort Worth, TX Posts: 5,261 Reputation: 3386 Power: 199	Re: usb power question Usb standard dictates 5V voltage, voltage limits, power quality and maximum draw of 5W. The pocket PC should not try and draw more than 5W so it should work. Skim thorugh the manual for the pocket PC and see if it says anything different. The cigarette lighter plug adapter should specify it has a 5V, 5W output on the case. If it doesn't it may put out a higher voltage that could damage the pocket PC. The GPS and Pocket PC manuals should specify what is expected on the power interfaces. When all else fails. Can you plug either device into your dektop and recharge it? If yes, they both will work off of the USB standard. Standards are great, unfortunately not everybody follows them... Personally I would get a meter and measure the output from the USB charger with it plugged in if you can. Those pins are not real accessible. I fit reads under 6V with no load on it then you should be safe. Thought for the new millenium: In a world without walls and fences, who needs Windows and Gates? - Open Office - Firefox - Thunderbird - Gimp -Ubuntu - Red Hat -

January 31st, 2008	Top \| #3
perris OSNN Godlike Veteran Joined: January 2002 Location: new york Posts: 12,258 Reputation: 4333 Power: 291	Re: usb power question Originally Posted by LeeJend Usb standard dictates 5V voltage, voltage limits, power quality and maximum draw of 5W. The pocket PC should not try and draw more than 5W so it should work. Skim thorugh the manual for the pocket PC and see if it says anything different. The cigarette lighter plug adapter should specify it has a 5V, 5W output on the case. If it doesn't it may put out a higher voltage that could damage the pocket PC. The GPS and Pocket PC manuals should specify what is expected on the power interfaces. When all else fails. Can you plug either device into your dektop and recharge it? If yes, they both will work off of the USB standard. Standards are great, unfortunately not everybody follows them... Personally I would get a meter and measure the output from the USB charger with it plugged in if you can. Those pins are not real accessible. I fit reads under 6V with no load on it then you should be safe. thanx leejand, that answers the question perfectly, yes, both get charged from laptop IT'S NOT WHAT YOU'VE DONE IT'S WHAT YOU ARE GOING TO DO

January 31st, 2008	Top \| #4
Taurus hardware monkey Joined: May 2002 Location: Sacramento, CA Posts: 3,206 Reputation: 90 Power: 155	Re: usb power question Originally Posted by LeeJend Usb standard dictates 5V voltage, voltage limits, power quality and maximum draw of 5W. i thought it was 500mA, so 2.5W..? edit: Originally Posted by wikipedia The USB specification provides a 5 V (volts) supply on a single wire from which connected USB devices may draw power. The specification provides for no more than 5.25 V and no less than 4.75 V (5 V±5%) between the positive and negative bus power lines.[10] Initially, a device is only allowed to draw 100 mA. It may request more current from the upstream device in units of 2 mA up to a maximum of 500 mA.

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