1. Presenters: Jerald Thomas, Steve Jungst April 25, 2014 1 Abstract: Thyristor devices are common, yet largely misunderstood semiconductor devices. In this presentation we go into the background, lithography and structure, basic operations, and finally common applications of the thyristor. At the end we will give our concluding thoughts as well as five key concepts related to the thyristor that we believe all EE students should understand.

2. Thyristor origins, background and family Semiconductor structure Basic operations Applications Questions 2

3. Thyristor – “thyratron” + “transistor” 3 Attribution: Eric Barbour Attribution: Benedikt Seidl

4. Proposed by William Shockley in 1950. Physically created by General Electric in 1956. Popularized in the 1960’s. 4 Source: Stanford News Service

5. 5

6. 6 Source: Semiconductor Physics and Devices: Basic Principles

7. 7 Attribution: Mikhail Ryazanov Source: electrodata.blogspot.com

8. 1. Reverse Blocking Mode 2. Forward Blocking Mode 3. Forward Conducting Mode 8 Source: Semiconductor Physics and Devices: Basic Principles

9. High current and high voltage Controlling AC currents Snubber circuits Motor speed controllers Light dimmers Pressure-control systems/ liquid-level regulators 9 Source: www.helvar.nl Source: www.belimo.pl

10. 10 Attribution: Steve Jungst

11. The thyristor is a unique device, with a unique lithography, capable of many applications. Applications regarding alternating current with lower frequencies are where the thyristor really stands above others. 11

12. 12 Source: Google Patent Search

13. A SCR will continue to conduct current across the anode-cathode junction when the gate potential has been removed as long as the aforementioned current is above the thyristor latching current. When compared to a transistor, a thyristor has lower switching speeds. Thyristors main application area is regarding alternating current A thyristor has three main modes of operation: forward blocking, reverse blocking, and forward conducting. The thyristor is the successor to the thyratron, a gas filled tube device that could switch large currents using a small control voltage. 13

14. Neamen, Donald A. "15.6 | THE THYRISTOR." Semiconductor Physics and Devices: Basic Principles. 4th ed. Vol. 1. New York, NY: McGraw-Hill, 2012. 691-701. Print. Poole, Ian. "What Is a Thyristor or Silicon Controlled Rectifier, SCR." What Is a Thyristor. Radio-Electronics.com, n.d. Web. 19 Apr. 2014. "Thyristor Basics." PowerGuru. N.p., 12 Sept. 2012. Web. "Thyristor." Tech-FAQ. Tech-FAQ, 27 Sept. 2012. Web. 20 Apr. 2014. "What Is a Thyristor, SCR?" :: Electronics and Radio Today. N.p., n.d. Web. 22 Apr. 2014. 14