How much voltage and current the device can accept depends on successful communication with the adapter.
Generally speaking, the charging speed of USB C to C is faster than that of USB A 2.0 to USB C, but the charging speed of USB C to C is compared with that of USB A 3.0 to USB C. It depends on the interface protocol.
The maximum USB interface power is 100W, but USB 3.1 Gen2 is required to achieve this data. The USB 2.0 interface can provide a current of 5V0.5A, which is 2.5W, the USB 3.0 interface can provide a current of 5V0.9A, up to 4.5W, and the USB3.1 interface can provide a computer with a maximum of 20V5A, so the maximum power is 100W.
USB Type-C is a new interface type introduced with the USB3.1 connector. The Type-C specification is indeed formulated following the USB3.1 standard, but Type-C is not equal to USB3.1.
USB Type-C is just a form of the interface device, not a new standard, and the USB 3.1 standard still has Type-A and micro-B interfaces.
To increase the speed of battery charging, the power input to the battery must be increased. According to the power P=voltage V*current I, so to realize high-power fast charging, you need to work on both voltage and current. The first batch of fast charging solutions launched was based on the promotion of the two.
Method 1: Increase the Current
Boosting current is the easiest way to increase power. Qualcomm Quick Charge (QC) technology uses this principle. After detecting the D+D- of the USB, the identification of the fast charging protocol is completed and the fast charging mode is entered. But such fast charging can no longer keep up with the demand speed of 2020 and must be faster. However, due to the limitation of wires, this demand cannot be met.
Method 2: Boost the Voltage
Because the direction of the boost current was restricted, everyone turned their attention to boost voltage. There are many "outputs" in this direction. The Quick Charge 2.0 (QC2) technology from Qualcomm supports up to 9V2A (18W).
The QC fast charging protocol we saw on Android phones has not changed much in the first two generations of this fast charging technology, but it is the fast charging technology that dominates the smartphone field after the third generation. QC 3.0 adopts the voltage intelligent negotiation algorithm (INVO), and the input voltage is self-adjusted at 200mV, which further facilitates manufacturers to adjust the fast charging according to their products. QC4.0 increases the charging speed by 20% and the efficiency by 30% on this basis. Android phones, basically most phones can use Qualcomm QC3.0 for fast charging.
PD can be said to be an all-around fast charge. In addition to the fast charging function for Apple mobile phones (you must have an original Apple or Apple-authorized USB-C to lightning data cable), it is also compatible with all mainstream fast charging protocols on the market such as QC3.0, Huawei, Samsung. It is output through the USB-C port. The biggest difference between USB-C and the USB-A port used by most chargers is that it supports high current. So basically, as long as the PD is used, most mobile phones charge super fast and can reach the highest current that the mobile phone system can recognize.
Therefore, the charging device using the QC3.0 protocol of the USB A interface can realize the fast charging of Android devices, and the PD protocol of the USB C interface can also realize the fast charging of iOS devices.
The charging speed is related to the interface type. The charging speed of the USB A 2.0 interface is slower than that of USB A 3.0 and USB C, and the PD protocol of USB A QC3.0 and USB C can realize fast charging.