USB type-c devices are also becoming increasingly popular in the real world, with many popular mobile phones and tablets adopting USB type-c interfaces. I expect that the number of products using the USB Type-C interface will increase rapidly in the next few years.

Why is the power 15W (5V3A)?

In addition to having a reversible plug, the USB Type-C adapter delivers more power than any previous USB version. While USB Type-C can support up to 100W for USB 3.1 and USB charging, system designers must carefully select features to keep overall costs reasonable.

The USB Type-C interface uses 15W power, which is six times the charging rate of standard USB 2.0. For most smartphones and tablets, 15W is sufficient and the cost is reasonable.

Diode rectification and PSR are widely used in adapters with currents below 2A.

The normal power of previous mobile phone power adapters was 5V/2A or lower. Primary-side regulation (PSR) is often used for AC/DC conversion because of its simplicity, which allows the elimination of optoisolators and programmable references. Because the load current is not high, a diode rectifier is used at this power level