Switching characteristics, Electrical Engineering

Assignment Help:

Switching Characteristics

Switching  characteristics  of BJT  are shown  in figure. Due  to the presence of internal  capacitances BJT  cannot be  turned  instantly. Initially when base  emitter  voltage  is applied in CE  configuration leakage current  flows.  The collection current  begins  to rise after  some delay  time  and reaches at its  steady state  value. the time  from which  collector  current  starts  rising  to its  steady  state value  known  as rise time. BJT gets turned on in and collector emitter  voltages falls from  its maximum  value  forward voltage drop.

1431_Switching Characteristics.PNG

 

Till the forward  base  current is  maintained the BJT  remains in  on condition. As  the base emitter  voltage  is removed at a time t1 does not change for a  time ( there  its is  storage time in which the charges are removed from the base).  After  this time Ic begins to fall and collector voltage starts rising  for a time tf  ( fall time ) . in  fall time  decreases to leakage current  and voltage  rises  to vcc. Hence the turn off time  of BJT is  t off = ts +  tf. In conduction period of BJT a steady state  current  flows and  forward  voltage  drop  appears across the  collection emitter  junctions.

 


Related Discussions:- Switching characteristics

Inductive coupling, advantages and disadvantages of inductive coupling

advantages and disadvantages of inductive coupling

Sketch the asymptotic bode diagrams, Q. Sketch the asymptotic Bode diagrams...

Q. Sketch the asymptotic Bode diagrams for the following functions:

What are macros, What are Macros? Macro is a group of instruction. The ...

What are Macros? Macro is a group of instruction. The macro assembler makes the code in the program each time where the macro is called. Macros are described by MACRO & ENDM di

Formation of energy bands in solids, Describe in brief the Formation of ene...

Describe in brief the Formation of energy bands in solids and hence explain how it helps to classify the solid in to conductors and insulators. Energy Bands in Solids Acco

Single-axis autopilot control system of an aircraft, Q. Single-axis autopil...

Q. Single-axis autopilot control system of an aircraft? Figure (a) shows the block diagram of a simplified single-axis (pitch, yaw, or roll) autopilot control systemwith digita

What are loosely coupled systems, What are loosely coupled systems? In ...

What are loosely coupled systems? In loosely coupled systems every CPU may have its own bus control logic. The bus arbitration is handled by an external circuit, common to all

Mesh analysis, i am battling with mesh, node anaalysis, superposition, node...

i am battling with mesh, node anaalysis, superposition, node thevenin and norton equivalents

How to calculate new current and terminal voltage?, Q. Series generator hav...

Q. Series generator having a combined armature and field resistance of 0.4? is running at 1000 r.p.m. and delivering 5.5kw at terminal voltage of 110 V. If the speed is raised to 1

Find dispersion relation for free electron, Find Dispersion Relation for Fr...

Find Dispersion Relation for Free Electron Question: Find the dispersion relation for a free electron, and, thus, observe the relation between its rest mass and effective ma

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd