USB flash drive storage principle

- Nov 30, 2018 -

The computer converts the binary digital signal into a composite binary digital signal (adding instructions such as allocation, verification, stack, etc.), reads and writes to the USB chip adaptation interface, and stores the binary data through the chip processing signal to the corresponding address of the EEPROM memory chip to realize the data. storage. EEPROM data memory, the control principle is the voltage control gate transistor voltage high and low value, the gate transistor junction capacitance can save the voltage value for a long time, the reason for saving data after power off is mainly to add floating gate and selection on the original transistor Grid. A floating gate storing electrons is formed on the semiconductor whose current is unidirectionally conducted between the source and the drain. The floating gate is covered with a silicon oxide film insulator. Above it is a selection/control grid that controls the transfer current between the source and drain. The data is 0 or 1 depending on whether there is electrons in the floating gate formed on the silicon substrate. There is an electron of 0 and no electron of 1.

Flash is just like its name, and data is deleted for initialization before writing. Specifically, electrons are derived from all floating gates. The data will be returned to "1". When writing, only data is 0, and when the data is 1, nothing is done. When 0 is written, a high voltage is applied to the gate electrode and the drain to increase the electron energy conducted between the source and the drain. In this way, the electrons will break through the oxide film insulator and enter the floating gate. When reading data, a certain voltage is applied to the gate electrode, the current is as large as 1, and the current is set to zero when the current is small. In the state where the floating gate has no electrons (data is 1), a voltage is applied to the drain when a voltage is applied to the gate electrode, and a current is generated between the source and the drain due to a large amount of electrons moving. In the state where the floating gate has an electron (data is 0), the electrons conducted in the channel are reduced. Since the voltage applied to the gate electrode is absorbed by the floating gate electrons, it is difficult to affect the channel.

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