Lecture #28The Silicon Controlled Rectifier (Thyristor)SCR OperationForward blocking stateConducting StateQuantitative AnalysisSlide 7EE130 Lecture 28, Slide 1Spring 2007Lecture #28ANNOUNCEMENTS•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 partnerOUTLINE•The PNPN thyristorReading: Chapter 13EE130 Lecture 28, Slide 2Spring 2007The Silicon Controlled Rectifier (Thyristor)•The SCR is a PNPN device–Used in high-power switching applicationsEE130 Lecture 28, Slide 3Spring 2007•The SCR can be modeled as 2 interconnected BJTsSCR OperationEE130 Lecture 28, Slide 4Spring 2007Forward blocking state•Few holes injected into N region•Thermal R-G current onlyEE130 Lecture 28, Slide 5Spring 2007Conducting State1. Holes injected into N2. Due to wide N-P depletion region, holes are swept into P, turning on PNP device3. This turns on NPN device•This regenerative effect maintains conduction even at low voltage, down to a minimum “holding current”.EE130 Lecture 28, Slide 6Spring 2007Quantitative Analysis•We can write:•Normally, (1+2) <1•However, as VAK , base width narrowing causes (1+2) 1, IAK 2102010220111RRAKRAKRAKAKIIIIIIIIEE130 Lecture 28, Slide 7Spring
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