The Tronsmart Presto 10400mAh USB-C Power Bank offers a simple approach to support charging over USB Type-C without having to use active USB Power Delivery negotiation. The power bank when plugged in with a USB Type-C AC charger just uses simple CC line voltage levels to communicate as it receives USB Type-C signals from the charger or passes USB Type-C signals to the attached phone.
The Tronsmart Presto 10400mAh USB-C Power Bank uses a USB Type-A port to provide fast charging using Qualcomm Quick Charge 3.0 technology to any of the many phones that support Qualcomm Quick Charge. The USB Type-C port is used to charge the Tronsmart power bank or charge other phones that support 15 watts of charging (5 volts @ 3 amps) that is supported just by using USB Type-C. Note this USB Type-C port doesn't support Qualcomm Quick Charge 3.0 or USB Power Delivery. When charging the Tronsmart power bank using the same USB Type-C port, you can use a 15 watts (5 volts @ 3 amps) charger.
When using Qualcomm Quick Charge 3.0 technology, the USB Type-A port provides the following charging capabilities: 5-6.5 volts @ 3 amps, 6.5-9 volts @ 2 amps and 9-12 volts @ 1.5 amps, thus providing a max of 19.5 watts (6.5 volts @ 3 amps).