Avalanche Breakdown

Avalanche Breakdown is a type of breakdown usually seen in PN junctions which are connected in reverse bias.  When the reverse bias voltage exceeds the peak inverse voltage of the PN junction, the junction will break.

When a PN junction is connected in reverse bias i.e. the P material to the cathode and the N material to the anode, the size of the depletion region becomes maximum and the current becomes very low.  The electron-hole pairs which cross over to the depletion layer are drawn to opposite sides.  The acceleration of these charge carriers depends on the electric potential.  

At high potentials, the electron can collide against atoms and consequently cause other electrons to get knocked out.  These electrons in turn will collide with other atoms and knock out more electrons.  The process continues until more and more electrons are knocked out.  This ultimately leads to the failure of the PN junction.

This is a common mechanism of failure of diodes connected in reverse bias.  Hence, the Peak inverse voltage of diodes should be checked against the maximum voltage they would have to withstand.  




Posted by: Electrotechnik

EEPROM

EEPROM stands for Electrically Erasable Programmable Read Only Memory.  It is also called E2PROM.  EEPROM is a type of Read Only Memory.  The data in an EEPROM can be erased by applying an electric charge to it.  

The data in an EEPROM needs to be erased one byte at a time.  In contrast, in Flash Memory, the data is erased and written in blocks which makes it faster.



Posted by: Electrotechnik

Spark Plug

The Spark Plug is the device which generates the spark for combustion of fuel in an internal combustion engine.  The spark is generated by the high voltage which is supplied to the spark plug by the ignition coil.

The Spark Plug contains a central electrode which is enclosed in a porcelain body.  The metal shell of the spark plug is connected to the engine block or the cylinder head and is thus electrically grounded.

The spark gap is the location where the spark appears.  The gap is formed by the central electrode and the electrode from the grounded body.  The gap between the two electrodes is very small.

When the high voltage from the Automobile ignition coils is applied to the the central electrode, the high voltage causes an arc to form across the two electrodes.  

This spark ignites the fuel/air mixture in the engine.  

The spark gap experiences very high temperature during the spark.  Hence, special materials and fabrication techniques are adopted in its manufacture.  




Posted by: Electrotechnik

Flash EEPROM

The Flash EEPROM or Flash Memory as it is popularly known is a type of Electrically Erasable Programmable Read Only Memory.  It is different from conventional EEPROMs in that the memory can be erased quickly, in a "flash".  Hence its name.  Flash EEPROMs are widely used in computers, in electronic devices such as cameras, cellphones and camcorders.

Flash EEPROMs are continually being made in smaller sizes.  Pen Drives are an example of Flash EEPROMs



Posted by: Electrotechnik

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