1. SMART LIGHTING 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. K. A. Connor15 September 2015 Outline Diodes – What is their basic function? Current flows one way. How Stuff Works – RPI Connection PN Junction Diode I-V Characteristic LEDs

3. K. A. Connor15 September 2015 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 … Diodes

4. K. A. Connor15 September 2015 In effect, diodes act like a flapper valve Note: this is the simplest possible model of a diode Diodes

5. K. A. Connor15 September 2015 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) Diodes

6. K. A. Connor15 September 2015 10 volt sinusoidal voltage source Connect to a resistive load through a diode This combination is called a half-wave rectifier Diodes

7. K. A. Connor15 September 2015 Sinusoidal Voltage Diodes

8. K. A. Connor15 September 2015 Half-wave rectifier Diodes

9. K. A. Connor15 September 2015 How Stuff Works: LEDs

10. K. A. Connor15 September 2015 A Little History Note The Former Name!

11. K. A. Connor15 September 2015 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. K. A. Connor15 September 2015 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. K. A. Connor15 September 2015 PN Junction When connected in the other direction, electrons collect on one end and holes on the other and the depletion zone grows

14. K. A. Connor15 September 2015 Diode I-V Characteristic For ideal diode, current flows only one way Real diode is close to ideal Ideal Diode

15. K. A. Connor15 September 2015 LED Advantages? Differences from other diodes? Today

16. K. A. Connor15 September 2015 LED Wikipedia

17. K. A. Connor15 September 2015 LED I-V Characteristics LED Tutorial Linear LED Calculator