GTrusted
The Windows based Microsoft Surface Book 2 can expand its connectivity options by attaching an external dock such as the CalDigit Type-C Dock through its USB Type-C port. The CalDigit Type-C Dock supplements the 2-in-1 Surface laptop with Ethernet, USB, HDMI, and audio ports as well as USB Power Delivery charging through a single USB Type-C cable.
Using the GRL-USB-PD-A1 power analysis software from Granite River Labs, let's zoom in on the initial USB Power Delivery communications between the CalDigit Type-C Dock and the Microsoft Surface Book 2 when connected over USB Type-C.
At the beginning, we can see Vendor Defined Messaging takes place to adjust voltage and current which then follows by the CalDigit Type-C Dock offering 15 watts (5 volts @ 3 amps) to the Microsoft Surface Book 2 while being 30% charged.
By first requesting 0 watts (5 volts @ 0 amps), the Microsoft Surface Book 2 oddly doesn’t want to use the power offered by which the CalDigit still complies.
After a Power Role Swap and soft reset, we again observe voltage and current being adjusted over Vendor Defined Messages which eventually triggers the CalDigit Type-C Dock to finally display its full power profiles of 15 watts (5 volts @ 3 amps), 36 watts (12 volts @ 3 amps), and 60 watts (20 volts @ 3 amps).
The Microsoft Surface Book 2 takes advantage of the higher power available to request 39 watts (20 volts @ 1.95 amps) charging power which the CalDigit subsequently accepts.
After a soft reset, we can see a long list of Vendor Defined Messages being exchanged which also shows both the charger and PC supporting the DisplayPort Alt Mode.
When we first connect the Microsoft Surface Book 2 with the CalDigit Type-C Dock, starting with a 30% charged battery, the PC begins pulling quick current of about 2.4 amps at 20 volts which later settles out charging at around 38 watts (20 volts @ 1.9 amps) when the PC is on.
The CalDigit Type-C Dock is able to successfully pass through the USB Power Delivery negotiation sequence to effectively charge the Microsoft Surface Book 2 at around the max power that the PC can expect to get from its own Surface AC adapter accessory for rapid charging.
