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.