Conmari
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Powering a USB monitor
I'm considering purchasing a portable PC monitor that is powered through a USB connection vs. a separate AC adapter. The specs for the unit say power usage is 8 watts max. It comes with a USB cable that combines two male connectors (a Y configuration) such that one or both can be connected to the PC, depending upon the power output of the PCs ports. The other end of the USB cable is connected to the monitor. I wish to use this with a Toshiba NB300-N300 netbook that is about 5 years old and has 2 USB 2.0 conventional ports and one USB 2.0 charging port. I normally have one of these ports used for a wireless mouse and another for a wireless keyboard. This would leave only one free port for the monitor.
The website for the monitor manufacture does not provide a means to ask product questions without having proof of purchase (serial number). Reading user reviews on vendor websites, some have had to use both USB connectors a the PC end. I understand that USB 2.0 ports will supply 100mA at 5V without negotiation between a device and the controller, or up to 1/2 watt. Up to 500mA (2.5 watts) can be supplied to a device through negotiation with the controller though some manufacturers will allow for greater output. Toshiba tech support says they don't have a maximum output spec available. So, even if I connect both USB connectors from the monitor, it seems that I can only count on a maximum of 5 watts being supplied to the monitor. However, I don't have 2 ports available if I have both the wireless keyboard and mouse connected.
I'm wondering whether I would be able to use an AC/USB power adapter with higher maximum output (12W?) to provide power to the monitor through one of the USB connectors and plug the other side of the Y to connect to the netbook port to supply the data.
It may be difficult to provide a definitive answer but I'm trying to do what I can to avoid a blind trial-and-error situation.
The website for the monitor manufacture does not provide a means to ask product questions without having proof of purchase (serial number). Reading user reviews on vendor websites, some have had to use both USB connectors a the PC end. I understand that USB 2.0 ports will supply 100mA at 5V without negotiation between a device and the controller, or up to 1/2 watt. Up to 500mA (2.5 watts) can be supplied to a device through negotiation with the controller though some manufacturers will allow for greater output. Toshiba tech support says they don't have a maximum output spec available. So, even if I connect both USB connectors from the monitor, it seems that I can only count on a maximum of 5 watts being supplied to the monitor. However, I don't have 2 ports available if I have both the wireless keyboard and mouse connected.
I'm wondering whether I would be able to use an AC/USB power adapter with higher maximum output (12W?) to provide power to the monitor through one of the USB connectors and plug the other side of the Y to connect to the netbook port to supply the data.
It may be difficult to provide a definitive answer but I'm trying to do what I can to avoid a blind trial-and-error situation.
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nobus
ok - interested in the outcome
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ASKER
Here's some information from the manufacturer:
* No reports received from field about power problems. (I have read other user reports that both USB connectors need to be plugged in to the PC.)
* 2.5 - 8w power required, depending upon application. (1A from two USB 2.0 ports combined equates to 5w which is adequate in most situations.)
* A powered USB hub can be used to supply additional power if needed. 1A per port would guarantee that. (1A from the hub and .5A from the laptop equates to 7.5w @ 5V.)
* The monitor will not operate if there is inadequate power. They also say that the USB controller will shut down if too much current is drawn. (I have not verified that with Toshiba but I have found the following Q&A links which refer to the USB spec:
http://electronics.stackexchange.com/questions/53747/is-it-safe-or-even-possible-to-draw-more-power-from-a-usb-port-than-it-was-des
http://www.microchip.com/forums/m274097.aspx
I have also configured my Logitech wireless mouse and keyboard to operate from a single dongle through their unifying utility so that I will have two free USB 2.0 ports available for use with a portable monitor.
Based on the above, I'm going to purchase the AOC unit and will report back the results.
* No reports received from field about power problems. (I have read other user reports that both USB connectors need to be plugged in to the PC.)
* 2.5 - 8w power required, depending upon application. (1A from two USB 2.0 ports combined equates to 5w which is adequate in most situations.)
* A powered USB hub can be used to supply additional power if needed. 1A per port would guarantee that. (1A from the hub and .5A from the laptop equates to 7.5w @ 5V.)
* The monitor will not operate if there is inadequate power. They also say that the USB controller will shut down if too much current is drawn. (I have not verified that with Toshiba but I have found the following Q&A links which refer to the USB spec:
http://electronics.stackexchange.com/questions/53747/is-it-safe-or-even-possible-to-draw-more-power-from-a-usb-port-than-it-was-des
http://www.microchip.com/forums/m274097.aspx
I have also configured my Logitech wireless mouse and keyboard to operate from a single dongle through their unifying utility so that I will have two free USB 2.0 ports available for use with a portable monitor.
Based on the above, I'm going to purchase the AOC unit and will report back the results.
i found most laptops do not provide the max, and stay well below it
i would never recommend loading the usb port like this
i would never recommend loading the usb port like this
ASKER
Question status: Just received the monitor and hope to install and try out later today. Will report what I find as soon as possible.
ASKER
Have installed the included driver and monitor utility and connected the monitor using both USB connectors of the Y cable provided. Monitor works great. Quality reasonably good -- about what one would expect for the price ($90). Did have a possible problem with initial drive install (a Norton Internet Security program error ensued, though not sure about the cause and effect). Uninstalled/reinstalled the driver and utility and problem has not recurred.
Want to get some more time with this before I pass judgment but so far so good.
Want to get some more time with this before I pass judgment but so far so good.
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ASKER
All of the responses made me realize that more information was necessary which I ended up eventually getting from the manufacturer. In the end, this was still somewhat of a trial-and-error solution based on what I learned to give me a reasonable comfort level.