Pendrive:
A printed
circuit board carrying the circuit elements and a USB connector is shown in the
above image. The circuitry is protected inside a pair of plastic cases
(connected to each other by means of mechanical hooks) which can be carried in
a pocket or a key chain. The USB connector is protected by either retracting
into the body or by covering by a removable lid. There are two chips, one is
the USB controller and the other is the flash memory chip.
The IC SK6211
shown in the above image is a controller which facilitates the data
communication between the PC/Laptop and the flash memory (EEPROM) of the pen
drive. It is fully compatible with USB 2.0 protocols and USB Mass storage class
V1.0 specification. The devices like memory card, hard disk, pen drive etc with
high data storage capacity fall under the category of Mass Storage Devices. In
order to communicate data with devices falling under this category the USB has
defined a set of protocols. The operating system provides inbuilt libraries to
handle such devices thereby preventing the need of any external drivers to be
installed before using these devices. This controller IC can interface with all
kind of NAND EEPROM.
The second
chip which is shown in the image above is a NAND type flash memory which has
fast read, write and erase cycles. The data is stored in memory cells of the
EEPROM, known as “floating gate transistors” - a regular metal-oxide field
effect transistor (M0SFET) consisting three terminals - source, gate and drain.
The storage capacity of this memory is 2GB. There is another similar chip with
storage capacity of 2GB on the other side of the PCB, thereby making the total
capacity of the pen drive to be 4GB.
The above
image shows the other side of PCB. The second memory chip, a crystal oscillator
and a number of surface mount components are soldered which are required for
the operation of the pen drive.
The crystal
oscillator produces the clock signal for the correct operation of the device.
The crystal oscillator used here runs at a clock frequency at 12 MHz.
Hardwork Can Never Ever Fails..
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