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It’s interesting to see how the Apple 87W USB-C Power Adapter (that originally came with the Apple 15" MacBook Pro (Late 2016)) works with other non Apple products, especially main rival Samsung with their recently released Samsung Galaxy Note 8 phone. With USB Power Delivery fast charging supported by both the Apple 87W USB-C Power Adapter and Samsung Galaxy Note 8, let’s take a look at what goes on when these devices are directly connected with a USB Type-C to Type-C cable.

From the USB Power Delivery protocol transactions as seen via the Granite River Labs GRL-USB-PD-A1 analyzer, the Apple 87W USB-C Power Adapter initiates communication with the Samsung Galaxy Note 8 by offering a single 12 watts (5 volts @ 2.4 amps) power option.

Without hesitation, the Samsung Galaxy Note 8 starts to request this 12 watts (5 volts @ 2.4 amps) charging from the Apple charger and gets accepted.

After several Vendor Defined Messages to adjust voltage and current, we then see the Apple 87W USB-C Power Adapter declares to support two more power profiles of 27 watts (9 volts @ 3 amps) and 86 watts (20 volts @ 4.3 amps) along with the initial 12 watts (5 volts @ 2.4 amps).

At first, the Samsung Galaxy Note 8 still makes the same 12 watts (5 volts @ 2.4 amps) power deal with the Apple charger, but after the next power offering by the charger, only then the phone finally requests to charge faster using 27 watts (9 volts @ 3 amps) which the charger also complies. After this, we can also see Discover Identity and SVIDs being exchanged between the charger and phone.

When the Samsung Galaxy Note 8 is first plugged in at power on, USB Power Delivery negotiations begin when the phone starts off pulling a brief 12 watts (5 volts @ 2.4 amps). Over Vendor Defined Messages and same power requests, the phone pulls lower current down to about 0.7 amps while at 5 volts. As the 27W request is made, the voltage goes up to reach around 9 volts while the current still stays at about 0.7 amps. When the phone goes into sleep mode, it pulls higher current to charge at around 12.6 watts (9 volts @ 1.4 amps).

Although we never observe the phone pulling anywhere near 27W as established during initial power delivery negotiation with the Apple charger, the Samsung Galaxy Note 8 is able to charge with the Apple 87W USB-C Power Adapter at almost 13 watts, which also happens to be around the power offered by the Samsung's supplied Adaptive Fast Charger through Samsung's proprietary charging scheme.