Just like most Apple devices, the iPhone uses an iPhone cable with a 30-pin connector for accessory connectivity, audio and video transfer, charging and synchronization. This is why generic USB cables cannot be used with an iPhone or any other Apple device. The connector at the end of this cable is also referred to as a “Mac Connector”. An iPhone USB cable is built to allow data transfer between a computer and an iPhone, and to charge an iPhone as well.
The USB Plug
The other end of an iPhone cable has a USB plug, which is a standard connect that can be found on almost any computer and laptop. It is the main input and output port for communication with devices like the iPhone. The USB plug of the cable makes it synchronization possible between an iPhone handset, and a computer and the computer’s software. A regulated 5-volt output is also included in the standard USB plug of the cable, so an iPhone can be powered or charged while it is connected to a computer. For the cable’s computer end, any standard, 4-pin USB plug is required for the iPhone.
Apple specifically designed the proprietary 30-pin connector, mentioned above, for USB cables for all its devices. The USB cable used for data transfer and power on most of the Apple devices, including the iPhone, has this “Mac Connector”. Although there are only four pins in a standard USB cable, but the Mac Connector in an iPhone cable has extra connections between the pins. This makes it possible for the iPhone to receive a charging voltage, and communicate with an external device. The essential power and data system of an iPhone USB cable is the same as a standard USB cable; however, the connections between the two plugs tend to vary slightly.
USB to Mac Connections
An iPhone cable has a positive data line that connects the USB plug’s pin 3 to the Mac connector’s pin 27 to allow data transfer between an iPhone and an external device. The negative data line in the cable connects the USB plug’s pin 2 to the Mac connector’s pin 25. The USB cable’s pin 1 is connected to the Mac connector’s pin 23, allowing a power output of positive 5 volt to be achieved from the cable. Another wire connects the USB plug’s pin 4 to the Mac connector’s pin 16, allowing a negative power output to be achieved.
An iPhone cable also has resistors that are connected to the USB data lines where they provide a particular voltage signal so that a charging voltage can be accepted by an iPhone from the USB. The resistors make it possible for the iPhone to be charged via the cable, and also allow the iPhone to synchronize with an external device.
For people with a computer or any other compatible external device, transferring data between the device and their iPhone device becomes easier using an iPhone data cable. The iPhone USB cable can also be used as an alternate means of charging an iPhone. Thus, the iPhone cable is an integral iPhone accessory.