USB chargers are presently the most common devices that are used in charging Smartphones and tablets. The devices are of three main specifications: USB 1.0, 2.0, and 3.0. Of the three, USB 2.0 is the most familiar.

In the USB network, there is always the host and the device. For example, if you are using a computer to charge your phone, your PC becomes the host and your phone becomes the device.

If you are using a wall charger, the charger becomes the host and your tablet or phone becomes the device. At all times, power flows from the host to the device.

If you look closely, you will see that a USB socket has four pins. The USB cable also has four wires. The inside pins carry data (D+ and D-) while the outside pins supply power.

Charging process

It's good to note that different USB ports charge the devices attached to them differently. For instance, you will find that one port charges your phone fast while another port charges the same phone very slowly.

Two factors determine the speed at which your device charges over USB: the maximum amperage of the USB socket or wall charger and how your device brings up power from the charger.

All chargers have maximum amperage which is usually between 500 milliamps and 1.5 amps. In most cases, a PC has 500mA while the max amperage of a wall charger varies from one device to another. Although this is the case, the amperage of wall chargers is usually between 0.5A and 2.1A.

How your device negotiates with the charger greatly determines how your device charges. When you plug your device into the wall charger or charging socket, the USB controller in your device transmits with the USB controller attached to the charger.

If there is no controller, the device reads the voltage flowing across the USB pins, and from the data, the device determines the amount of amperage that it should draw.

Can a USB device blow up during charging?

The answer is No. You can plug any USB device into any USB cable and any USB port without any problems and your device won't blow up. This means that you can connect a smartphone that came with a 900mA charger into a 2100mA and the device won't blow up.

According to experts, connecting your device to a higher power source doesn't result in blowing up the device, but instead speeds up the pace at which the battery charges.