How USB Power Delivery Looks Like for the Dell 30-Watt AC Adapter with 3 ft Power Cord - USB Type-C
The Dell 30-Watt AC Adapter with 3 ft Power Cord - USB Type-C ships with the Dell XPS 12 9250 to provide charging through the PC's Thunderbolt 3 ports using the common USB Power Delivery profiles of 15 watts (5 volts @ 3 amps), 24 watts (12 volts @ 2 amps), and 30 watts (20 volts @ 1.5 amps).
To see how the Dell 30-Watt AC Adapter with 3 ft Power Cord - USB Type-C supports USB Power Delivery, we used the USB Power Test App from Granite River Labs with the Granite River Labs USB Power Delivery Compliance C2 Tester to generate the following test results.
The USB Power Test App first negotiates a power contract for every PDO supported by the Dell charger, and increases the load gradually to find the threshold where over current protection (OCP) kicks in and voltage and current start to drop for safety reasons.
The USB Power Test App reports out all the PDO's supported by the Dell charger and their OCP thresholds. OCP thresholds for the charger are set at about 25-87% above the maximum current levels for the fixed PDO's.
|PDO#1 Fixed: 5V 3A|
|PDO#2 Fixed: 12V 2A|
|PDO#3 Fixed: 20V 1.5A|
The USB Power Test App from Granite River Labs takes this data to produce an I-V curve which graphically shows the relationship between voltage and current for each PDO. We can observe as the current increases beyond the OCP threshold, the voltage immediately shuts off.
The USB Power Test App can also use the Granite River Labs USB Power Delivery Compliance C2 Tester integrated with the GW Instek APS-7100 programmable AC power supply to compare the charger's power output vs power input so that power efficiency can be measured and compared to regulatory limits from United States of Energy (DOE) Level VI or European Union's CoC Tier 2 requirements. We can repeat the power efficiency tests for different PDO's, current load conditions, and different AC input ranges, allowing us to get a complete picture of power efficiency ranges across all different usage scenarios.
Using the USB Power Delivery Compliance C2 Tester from Granite River Labs to run just a subset of the full USB Power Delivery compliance test suite, some compliance failures were observed for the Dell 30-Watt AC Adapter with 3 ft Power Cord - USB Type-C.
BMC Eye Diagram
The load trace below was captured using the GRL-USB-PD C2 Compliance Test Solution App which shows the Dell 30-Watt AC Adapter with 3 ft Power Cord - USB Type-C supporting various voltage and current levels for charging.