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Lecture #28

ANNOUNCEMENTS For Problem 2 of HW#9, use A = 10 -7 cm 2 The Term Project will be posted online today Due on Friday, April 27 You may work with one partner OUTLINE The PNPN thyristor Reading: Chapter 13. Lecture #28. The Silicon Controlled Rectifier (Thyristor).

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Lecture #28

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  1. ANNOUNCEMENTS For Problem 2 of HW#9, use A = 10-7 cm2 The Term Project will be posted online today Due on Friday, April 27 You may work with one partner OUTLINE The PNPN thyristor Reading: Chapter 13 Lecture #28 EE130 Lecture 28, Slide 1

  2. The Silicon Controlled Rectifier (Thyristor) • The SCR is a PNPN device • Used in high-power switching applications EE130 Lecture 28, Slide 2

  3. SCR Operation • The SCR can be modeled as 2 interconnected BJTs EE130 Lecture 28, Slide 3

  4. Few holes injected into N region Thermal R-G current only Forward blocking state EE130 Lecture 28, Slide 4

  5. Holes injected into N Due to wide N-P depletion region, holes are swept into P, turning on PNP device This turns on NPN device This regenerative effect maintains conduction even at low voltage, down to a minimum “holding current”. Conducting State EE130 Lecture 28, Slide 5

  6. We can write: Normally, (a1+a2) <1 However, as VAK, base width narrowing causes (a1+a2) 1, IAK Quantitative Analysis EE130 Lecture 28, Slide 6

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