Meizu was trying a lot of new approaches with the Meizu Pro 7 Plus but nothing prepared us for their very unconventional implementation of USB Power Delivery.
The latest Meizu Pro 7 Plus phone supports Meizu's owned mCharge 4.0 technology that works on MediaTek's Pump Express 3.0 platform that can deliver over 23W of fast charging through USB Power Delivery based communications. The Meizu phone also comes with its own USB Type-A based AC charger supporting 25 watts (5 volts @ 5 amps) and 10 watts (5 volts @ 2 amps) output and special USB Type-A to Type-C cable that needs to be used with this Meizu charger.
What surprised us with the Meizu Pro 7 Plus is that Meizu mapped the Meizu USB Type-A charger's D+/D- data pins into the CC pins in the phone through this special USB Type-A to Type-C cable. Today's USB Power Delivery implementations simply travel from one USB Type-C based charger to a USB Type-C based phone, and never travel over a legacy USB Type-A connector.
It makes you wonder why Meizu didn't start with just a standard USB Type-C based charger rather than having to go through the trouble of creating a special USB Type-A AC charger and cable just so that the CC pins of their USB Power Delivery chip end up talking to the CC pins of the phone. However, this seems to be a way for Meizu to create a proprietary charger that provides a faster charging experience than other USB Type-A chargers.
Here we see how the Meizu Pro 7 Plus phone on a fully drained battery performs with its own charger when connected directly using Meizu's owned USB Type-A to Type-C cable. We capture their USB Power Delivery Protocol transactions using the GRL-USB-PD-A1 software by Granite River Labs. The Meizu charger starts to initially declare 10 watts (5 volts @ 2 amps) and variable 4.98 to 9.96 watts (3-6 volts @ 1.66 amps) power profiles after a hard reset.
The Meizu Pro 7 Plus initially requests 7.5 watts (5 volts @ 1.5 amps) and gets accepted by the Meizu charger.
After exchanging Discover Identity's and SVIDs' with the charger, the Meizu Pro 7 Plus can also be seen to enter Alternate Mode by initiating VCONN Swap.
Later we also observe both the Meizu phone and charger communicate over multiple Vendor Defined Messages including Discover Identity's, SVIDs', Modes, and Unstructured VDMs' to adjust current and voltage.
Upon plugin from zero charge, the Meizu Pro 7 Plus first pulls a trickle charge of about 4.5 watts (5 volts @ .9 amps) when the phone is in a dead battery state.
After the phone starts booting up, USB Power Delivery negotiation occurs, resulting in charging at 7.5 watts (5 volts @ 1.5 amps).
As Vendor Defined Messages are exchanged, after 1 minute, the current quickly goes up to 5.3 amps while the voltage drops to 3.5 volts and increases with current to eventually settle out at 4.4 volts and achieve 23.3 watts (4.4 volts @ 5.3 amps).
It's good to see that the Meizu Pro 7 Plus is able to get over 23W of fast charging although it uses a proprietary implementation of USB Power Delivery over USB Type-A.