A Quick Look At USB Power Delivery Support of the Apple 87W USB-C Power Adapter
The Apple 87W USB-C Power Adapter ships with the Apple 15" MacBook Pro (2018) to provide USB Power Delivery 2.0 rapid charging to the Mac. Click here to see how well the 87W adapter delivers USB Power Delivery fast charging to the Mac through the Thunderbolt 3 port while connected using the supplied Apple USB-C Charge Cable (2m).
We can view more details on how the Apple 87W USB-C Power Adapter supports power using the USB Power Test App from Granite River Labs with the Granite River Labs USB Power Delivery Compliance C2 Tester to produce the following test results.
The USB Power Test App first negotiates a power contract for every PDO supported by the 87W adapter, 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 87W adapter and their OCP thresholds. OCP thresholds for the 87W adapter are set at about 6-54% above the maximum current levels for the fixed PDO's.
|PDO#1 Fixed: 5V 2.4A|
|PDO#2 Fixed: 9V 3A|
|PDO#3 Fixed: 20V 4.35A|
The USB Power Test App from Granite River Labs also produces an I-V curve which graphically shows the relationship between voltage and current for each PDO. We can see the voltage immediately shuts off once the current increases beyond the OCP threshold.