the Principle of operation and device USB stick
In this article, we will discuss the principle of operation and device is the USB stick, and also I will tell about the features of USB flash drive to other storage devices. C the appearance of the USB memory stick has been a revolution in ROM devices and a large number of people around the world appreciate the convenience of data portability in a compact and capacious flash drive, which is also resistant to environmental influences.
The first thing I would like to give a definition of flash drive, and then to talk about it especially in front of other storage devices.
The USB Flash Drive (USB flash drive, USB flash drive) — device for accumulation and storage of information. Transferred to the device the data resides and is stored in flash memory. For information usb stick you must connect your TV (Smart), computer, tablet or any other reader.
The main disadvantage of the USB flash drive can be attributed to limited cycle write/erase, but stored in the device can be considered an infinite number of times. The cycle of rewriting modern standards of today is limited from 10000 and up to 100000 times. If you take into account the minimum cycle overwrite (10000) that may seem to be to operate a number of more than enough. But in fact it is not.
Imagine a situation when you actively use the flash drive overwriting any data on it several times a day. Agree that in this operation, the number of cycles (10000) to update the information no longer seems so large. Although, in fairness, it should be said that for the average user a flash drive with a minimum limit of overwrite will last a long time.
Unfortunately, not all USB drives work out your due date honestly. Usually the culprits are the producers of little-known firms and companies with unknown origin that do not comply with technological norms for creating a permanent storage device (ROM). Very often our Chinese «friends», who like to make imitations of famous brands, don't follow the technology (not quality parts) and create a cheap storage device that prematurely fail.
What to look for when selecting a USB flash drive.
- Producer (company). To minimize premature failure of the USB flash drive , make your choice in favor of established companies that operate on the market more than one year. For example, it can be companies such as Kingston, Transcend, Corsair, Apacer…
- as well when selecting a usb flash drive please note what type of memory it is built. Well if it has a flash memory of NAND type, because this type of memory can perform about 100000 cycles of write/erase information.
In the USB-based flash drive to be flash-pamyati the type of NAND and a small microcontroller with built in ROM or RAM. Flash memory (Flash Memory) belongs to the class of EEPROM (Electrically Erasable Programmable Read-Only Memory) — electrically erasable reprogrammable memory device, ROM or EEPROM.
Основное достоинство этого устройства в том, что оно энергонезависимо, а значит ему не нужно электричество для хранения данных. Стоит сказать, что основная особенность EEPROM в том, что хранящуюся информацию в устройстве (mini SD, MMC, SD, USB-fleshka…) можно считать бесконечное количество раз, а вот количество записи к сожалению ограничено (мы уже с вами говорили о том how to choose SD card).
Is usually on the packaging indicate both. But not a rare case when only indicates the number of cycles or the type of memory.
- The type of memory cells. In ordinary flash drives (USB Flash Drive) use two types of memory cells MLC and SLC. Usually cheaper models of USB flash drives complement MLC (Multi-level cell — multi-level memory cells)cells, which can withstand about 10 thousand cycles. Well, as you may have guessed SLC (Single-level cell — single-level memory cells) cells that complement the more expensive models that can withstand up to 100,000 or more cycles write/erase.
If you are planning to buy a SSD drive (USB Flash Drive), I recommend you to read the article about that how to choose a reliable USB flash drive.
The working principle of the USB flash drive and its components.
As I have already mentioned that the basis of the USB drive is a flash memory of type NAND or NOR. In turn, the flash memory contains a silicon crystal on which is placed a field-effect transistor with floating and control gate isolated. It should say that the field-effect transistors have drain and source. Now the floating gate transistor is able to hold charge (electrons).
At the time of recording data on the control shutter positive voltage and some of the electrons are directed (moves) from the drain to the source, deviating to a floating gate. Some of the electrons overcomes the thin insulating layer and penetrate into the floating gate, where they remain for a long period of storage. The retention time is measured in years, but somehow it is limited.
The USB flash device is quite compact, mobile and provide the ability to connect to any computer that has a USB connector. The manufacturers to cater to potential customers, combining a USB drive with all sorts of trinkets, ornaments, toys and pens…
Device USB Flash drive consists of the following electronic components:
- The USB connector.
- The microcontroller.
- Chip (IC chip) flash memory.
- Quartz resonator.
- Switch (write protection).
- A place for memory chips (extra bed).
Next, I would like to elaborate on the main components of the usb flash drive and describe some typical symptoms of unstable operation USB Flash drive.
The components and symptoms of unstable operation USB Flash drive.
- PCB — a multi-layered printed circuit Board which serves as the basis for all is located (soldered) parts electronics. Has the following typical failure conditions: poorly executed installation of electronic components during deformation (bends, strokes) on the card leads to internal gaps around the conductors and unstable usb flash drive.
- USB connector — designed to connect the flash drive to the reader. When poor-quality installation of the connector breaks away from the tracks and soldering. Not long ago I was faced with this phenomenon.
- Microcontroller — a chip, which is responsible for managing NAND and transmission of information. Contains information about the manufacturer and type of memory, and also stores the necessary service information for the proper functioning of the flash drive. The fault controller most often occurs the failure of a flash drive.
- The symptoms characterizing its failure: the flash drive is defined as «unknown device» shows not the correct size (volume) of the storage or asks to insert a blank disc into the reader. Cause of failure of the controller (burns) — is poor nutrition, poor operation of the stabilizer and improper removal of the flash drive.
- Memory chip NAND flash — it is a non-volatile memory, which is responsible for storing information. After N-th number of time in case of malfunction or damage to the memory can be formed in damaged blocks (bad blocks). There are other possible causes of bad blocks, which is no longer possible to write/read information. Eliminate this problem by using specialized programs that will ultimately reduce the amount of memory, but will restore performance.
- Quartz resonator — is used to build the reference frequency, which is necessary for the operation of the controller logic and flash memory. In case of failure, the USB flash drive is detected as «unknown device» or is not defined at all(doesn't see the reader).
The benefits of USB flash drives:
- Small size, weight, portability.
- You can connect the drive to any reader (practically all of them have USB).
- Virtually no influence from external environment (dust, scratches, pollution).
- The USB flash drive can operate in a wide temperature range.
- Small dimensions allow to store a large amount of information.
- Low energy consumption.
- In comparison with hard disks, it is more resistant to external influences, vibration and shock.
- Ease of connection to the device.
- High-speed data access.
Disadvantages of USB flash drives:
- a Limited number of cycles of write and erase before failure.
- Limited term Autonomous data storage.
- The speed of writing and reading is limited by the bandwidth of the USB bus and the flash memory.
- Sensitive to radiation and electrostatic discharge (usually observed in everyday life, most often in the winter).
At the conclusion of the article I suggest You watch the theme video on the production of USB Flash drives on the Kingston Production plant.