First, this item we keep on calling a charger isn’t actually a chager, real charger is inside the device being charged. Check out what it is called here>>>>

However, phone “chargers” have been around for a long time. Originally, a USB data port could supply 2.5W of power for charging… because no one expected to be charging anything. They designed USB to power a mouse or a keyboard.

So gradually, most every phone maker built larger power supplies for charging. But there was no way to ask for more USB power under USB rules, so every phone maker came up with a different way to tell their phone it was on a 5W or greater supply,and it could go ahead and pull more current.

Once everyone on the planet had decided to charge their phones via USB ports, the USB organization decided to come up with their own, standard way of doing this. This was called the USB Battery Charging specification, and it was a simple way for a phone and power dongle to agree on at least 7.5W of power.

These all came pretty close to the current limits on USB cables. To even more power, we would need thicker wires and connectors or higher voltages. Qualcomm, the largest smartphone processor manufacturer, came up with a two-way protocol called Quick Charge, which communicates between phone and power supply to request up to 20V, rather than the usual 5V, for a maximum of 18W.

The USB organization more recently noticed that the USB jack is the standard DC power supply, more standard worldwide, in fact, than any other power connector. So they came up with the new USB power delivery spec that can deliver 60W or 100W, depending on the cable. That’s enough for a laptop, not just a phone. 

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