The document discusses the switching characteristics of power BJTs and provides an introduction to thyristors. It describes the construction of a thyristor as an electronic device with four layers and three terminals containing three junctions. The document also outlines the characteristics of thyristors such as latching current, holding current, and provides a two transistor model to explain the working operation of a thyristor.

1. BJT & THYRISTOR
BY JAWARIA TAHIR
F-14

2. Learning Goals:
 Switching characteristics of power BJT.
 Introduction of Thyristor.
 Construction of Thyristor.
 Characteristics of Thyristor.
 Two Transistor Model.
 Working operation

3. Switching characteristics of power BJT:

4. Turn-OFF & Turn- ON Characteristics:
 TURN (on) = td (on) + t (r1) + t (fv1) + t (fv2)

5. THYRISTOR:

6. THYRISTOR:
• Electronic device
• Four layers
• Three terminals
• Three junctions

7. SCHEMATICS:

9. CONSTRUCTION:

10. Table Summary:

11. Characteristics of Thyristor

12.  Latching Current:
Latching current is the minimum amount of current
required to turn- ON the device.
Holding Current:
Holding current is the minimum amount of current
required to keep the device ON. The device will
automatically turn OFF below this current level

13. IV-Timing Diagram:

14. Thyristor Operation: Two Transistor Model:

18. Working Operation: