USB, or Universal Serial Bus, is a popular interface, developed in the 1990s, used to connect your computer to electronic devices such as your phone, for charging, transfer of information, and so on.
They are found in all laptops and personal computers. Typically, a laptop’s USB ports are of two types - USB 2.0 and USB 3.0.
In USB 3.0, when any device is connected to a USB port, the port only supplies one unit of current, i.e. 150 mA initially (each unit is 100 mA in USB 2.0). Then, it increases in steps only after a 'digital negotiation'. Current supplied this way can go only upto 0.9A maximum. This is the reason laptops charge your devices very slowly.
However, when no data is being synchronized, it is possible to take more power from the laptop by disabling data sync. In fact, USB 3.0 ports on laptops can supply upto 1.5 A in this case.
How is it done?
When a phone/tablet is connected to a power source, it tries to read what type of power source it is; these are mainly of three types-
Standard Downstream Port which is meant for data sync
Charging Downstream Port which is meant for data sync and charging
Dedicated Charging Port (DCP) which is meant for only charging
For the phone to charge at maximum power, it has to 'see' a Dedicated Charging Port (DCP).
Different devices have their customized protocols to recognize DCP. Here are a few-
Battery Charging 1.0, 1.1, 1.2
Samsung Fast charging standard
Apple iPhone Fast charging standard
Apple iPad Fast charging standard etc.
The mobile device recognizes a DCP by reading the voltage on data lines. Normal wall chargers tie the data lines at the required voltage levels as per the standard demanded by the phone.
On a related note, one reason why some phones charge slowly when connected to another phone’s adaptor is because the adaptor may be using a different DCP standard. However, this is not the only reason- it could also be because the cable or the adaptor don’t support that much current.
MuConnect when set to fast charging mode, auto detects which type of standard the connected device follows, disconnects the data lines between laptop and phone and ties the data lines at the phone end at the required voltage, thus signalling the device to take more current. This helps charge your devices fast, even from a laptop.
We have finalized our electronics and here is a video
demonstrating how our fast charging feature works-
We have tested this for different phones and have recorded the charging current for each case in normal mode and fast charging mode-