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Diodes

Diodes. K. A. Connor Mobile Studio Project Center for Mobile Hands-On STEM SMART LIGHTING Engineering Research Center ECSE Department Rensselaer Polytechnic Institute. Intro to ECSE Analysis. Outline. Diodes – What is their basic function? Current flows one way.

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Diodes

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  1. Diodes K. A. Connor Mobile Studio Project Center for Mobile Hands-On STEM SMART LIGHTING Engineering Research Center ECSE Department Rensselaer Polytechnic Institute Intro to ECSE Analysis

  2. Outline • Diodes – What is their basic function? • Current flows one way. • How Stuff Works – RPI Connection • PN Junction • Diode I-V Characteristic • LEDs

  3. Diodes • A diode can be considered to be an electrical one-way valve. • They are made from a large variety of materials including silicon, germanium, gallium arsenide, silicon carbide …

  4. Diodes • In effect, diodes act like a flapper valve • Note: this is the simplest possible model of a diode

  5. Diodes • For the flapper valve, a small positive pressure is required to open. • Likewise, for a diode, a small positive voltage is required to turn it on. This voltage is like the voltage required to power some electrical device. It is used up turning the device on so the voltages at the two ends of the diode will differ. • The voltage required to turn on a diode is typically around 0.6-0.8 volt for a standard silicon diode and a few volts for a light emitting diode (LED)

  6. Diodes • 10 volt sinusoidal voltage source • Connect to a resistive load through a diode • This combination is called a half-wave rectifier

  7. Diodes Sinusoidal Voltage

  8. Diodes Half-wave rectifier

  9. How Stuff Works: LEDs

  10. A Little History Note The Former Name!

  11. PN Junction At the junction, free electrons from the N-type material fill holes from the P-type material. This creates an insulating layer in the middle of the diode called the depletion zone

  12. PN Junction When the negative end of the circuit is connected to the n-Type layer & the positive end to the p-Type, electrons & holes move, the depletion zone disappears & current flows

  13. PN Junction When connected in the other direction, electrons collect on one end and holes on the other and the depletion zone grows

  14. Diode I-V Characteristic • For ideal diode, current flows only one way • Real diode is close to ideal Ideal Diode

  15. LED • Advantages? • Differences from other diodes? Today

  16. LED • Wikipedia

  17. LED I-V Characteristics • LED Tutorial • Linear LED Calculator

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