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An earlier review confirmed the viability of using LG's 27 inch Class Ultra HD IPS 4K 27UD88-W Monitor as a 4K display for your Dell XPS 12 9250 Laptop. One of the selling points for USB Type-C is its ability to use USB Power Delivery technology to charge through the same cable that is used for data and video. Using Granite River Lab's Power Delivery test software we are able to see the communication between the two devices.
The Source Capability given by the LG Monitor offers 5 volts @ 2 amps, 12 volts @ 3 amps, and 19 volts @ 3 amps, for a total of 10, 36, and 57 watts respectively.
The XPS 12 requested the third PDO almost immediately, opting for 19 volts at an operational current of 1.5 amps.
Using an oscilloscope we can see that the voltage of 19 volts was met, but the current for the most part does not reach 1.5 amps. Occasionally, as captured by the screenshot above, the current will spike to as high as 1.6 amps, and then fall back down to about 1 amp. The LG 27 inch Class Ultra HD IPS 4K 27UD88-W Monitor has proven itself once again as a reliable companion for USB Type-C based computer like the XPS 12.
