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Important terms used in semiconductor devices:
1. Uni-polar,Bipolar
2.Unidirectional ,Bidirectional
3. Controlled ,Uncontrolled
Voltage blocking capability of a device is represented by Uni- polar and bipolar.
a. Uni-polar device:
A device that blocks either positive or negative voltage.
b. Bipolar device:
A device that blocks both positive and negative voltage.
Current allowing capability is represented by Unidirectional and Bidirectional.
a. Unidirectional device:
A device that allows the current in only one direction.
b.Bidirectional device:
A device that allows both the direction of current .
Uncontrolled device:
Operator has no control over the switch.
Controlled device:
Operator has control over the switch.
1. Why BJT is current controlled device?
Base current (IB) is responsible for getting output.
2. Why MOSFET and IGBT are Voltage controlled device?
Gate- Source voltage (VGS) is responsible for getting the output.(MOSFET)
Gate- Emitter voltage (VGE) is responsible for getting the output. (IGBT)
3.Why SCR is called Charge controlled Device?
Higher the magnitude of the gate current pulse, lesser is the time required to inject the charge and turning on the SCR .
By controlling the amount of charge we can control the turning on time of the SCR.
Applications of controlled switches:
1.BJT - Fully controlled Switch
High Power & Low frequency Applications
2. MOSFET - Fully controlled Switch
High Frequency & Low power Applications
3. IGBT - Fully controlled Switch
High frequency and High power Applications
4. SCR- Semi controlled switch
High power Applications ( Power handling capability is more as compared to all switches)
5 сен 2024
