NPN Transistor 2N2923 as a Switch

Transistor Switching Circuit Design

 2N2923 Characteristics / Parameters

Component CharacteristicsComponent Parameters
Type Designator2N2923
Transistor OutlinePackage TypeCASE:  TO-92, TO98
FamilyBJT, NPN
Material of TransistorSilicon
PolarityNPN
Maximum Power Dissipation600mW,  
Maximum Collector to Base Voltage25V
Maximum Collector to Emitter Voltage25V
Maximum Emitter Base Voltage5V
Maximum Collector Current100mA
Minimum hFE90
Maximum hFE180
FunctionAmplification / Switch
Manufacturers

  1. Central Semiconductor Corp.
  2. New Jercy Semiconductor Products Inc.
  3. Micro Electronics
  4. SPRAGUE
  5. GE Solid State

 Three modes of Operating Region of Transistors are:

  1. Active Region
  2. Saturation Region
  3. Cut-off Region

1- Active Region Characteristics:

  • In 'Active Region' , the transistor operate as an 'Amplifier'
  • The Junction Base-Emitter is forward Biased.
  • The Junction Collector-Base is Reverse Biased.

2- Saturation Region Characteristics:

  • ​​In 'Saturation' region, the transistor operates as an 'Closed Switch'.
  • The 'Base' Electrode is Connected to Supply Voltage [ Vcc ]
  • The Junction Base-Emitter Voltage is greater than 0.6V i.e VBE > 0.6V.
  • The Junction Base-Emitter is Forward Biased.
  • The Junction Collector-Base is Forward Biased.
  • Maximum Saturation Collector Current [ Ic ] flows, i.e [ Ic=Vcc/R]
  • This condition of transistor is act as a 'Fully-ON' and this is 'Saturation Region'.
  • Collector to Emitter Voltage [ VCE ] is approximately equal to Zero ideally. i.e [ VCE = 0V ]

​3- Cut-Off Region Characteristics:

  • In 'Cut-off' region, the transistor operate as an 'Open Switch'.​
  • The 'Base' Electrode is Grounded to zero Voltage [ 0V ].
  • The Junction Base-Emitter Voltage is less than 0.6V i.e VBE < 0.6V.
  • The Junction Base-Emitter is Reverse Biased.
  • The Junction Collector-Base is Reverse Biased.
  • No Collector Current [ Ic ] flows, i.e [ Ic=0 ].
  • This condition of transistor is act as a 'Fully-OFF ' and this is 'Cut-Off Region'.
  • Collector to Emitter Voltage [ VCE ] is approximately equal to Supply Voltage [ VCC ] [ VCE = VCC ]

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