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Tuesday, 2 August 2011

USB Flash Disk Fixing Part 1: Components


We all have some flash disks that is not working, or working with some problems, so at first I should start with flash disk components and their job so when we face the problems we can know which part/s is/are the reason of each problem.




Flash Disk Components:

  1. Male type-A USB connector - provides a physical interface to the host computer.
  2. Crystal oscillator - produces the device's main 12 MHz clock signal and controls the device's data output through a phase-locked loop.
  3. USB mass storage controller - implements the USB host controller. The controller contains a small microcontroller with a small amount of on-chip ROM and RAM.
  4. NAND flash memory chip - stores data. NAND flash is typically also used in digital cameras.
  5. Printed Circuit: is the circuit that connects all the above 4 parts all together.


The typical device may also include:
  1. Jumpers and test pins - for testing during the flash drive's manufacturing or loading code into the microprocessor
  2. LEDs - indicate data transfers or data reads and writes
  3. Write-protect switches - Enable or disable writing of data into memory
  4. Unpopulated space - provides space to include a second memory chip. Having this second space allows the manufacturer to use a single printed circuit board for more than one storage size device
  5. Some drives offer expandable storage via an internal memory card slot, much like a memory card reader.


How the Components of a USB Drive Work

The microcontroller chip of the USB flash drive performs a similar task as a PC's processor, also known as a CPU. Microcontrollers and CPUs perform a very important task in synchronizing Input/Output (I/O) operations, kind of like how your heart works to keep your blood flowing in and out at a pace that is not too fast or too slow for your body at its current state. The memory controller chip is the one that stores data statically, and does not need a battery or anything to maintain the memory inside of it using Floating Gate technology.
Perhaps upon reading the above, you have become a little confused. Well, Floating Gate technology makes the memory controller able to trap electricity (data) and store memory without any extra electricity necessary to be spared for it. Erasing works like this: the voltage is changed which releases the data. These changes in voltage are determined by the computer that you plug your USB flash drive inside of.

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