The Components of a USB Flash Drive

Essential components

 

There are typically four parts to a USB flash drive:

 

Male type-A USB connector — provides an interface to the host computer.

 

USB mass storage controller — implements the USB host controller and provides a linear interface to block-oriented serial flash devices while hiding the complexities of block-orientation, block erasure, and wear levelling, or wear balancing. The controller contains a small RISC microprocessor and a small amount of on-chip ROM and RAM.

 

NAND flash memory chip — stores data. NAND flash is typically also used in digital cameras.

 

Crystal oscillator — produces the device’s main 12 MHz clock signal and controls the device’s data output through a phase-locked loop.

 

Additional components

 

The typical device may also include:

Jumpers and test pins — for testing during the flash drive’s manufacturing or loading code into the microprocessor.

 

LEDs — indicate data transfers or data reads and writes.

Write-protect switches — indicate whether the USB flash drive should be in “write-protection” mode.

 

Unpopulated space — provides space to include a second memory chip. Having this second space allows the USB flash drive manufacturer to develop only one printed circuit board that can be used for more than one storage size device, to meet the needs of the market.

 

USB connector cover or cap — reduces the risk of damage due to static electricity, and improves overall device appearance. Some flash drives do not feature a cap, but instead have retractable USB connectors. Other flash drives have a “swivel” cap that is permanently connected to the USB flash drive itself and eliminates the chance of losing the cap.

 

Transport aid —the cap or the body often contains a hole suitable for connection to a key chain or lanyard. Connecting the cap, rather than the body, can allow the drive itself to be lost.

 

Some drives offer expandable storage via an internal memory card slot, much like a memory card reader.

 

The information above which is provided by a most professional USB flash drive manufacturer World Crown Electronics Ltd is just for your reference, for the source information, please refer to http://en.wikipedia.org .