1. 1 © Unitec New Zealand APTE 5601 &DE4401 S EMICONDUCTORS A TOMIC S TRUCTURE DIODES

2. Conductors, Semiconductors, Insulators 2 © Unitec New Zealand

3. Silicon Crystal Lattice- no free electrons 3 © Unitec New Zealand

4. N-type Silicon Doping –few free electrons 4 © Unitec New Zealand

5. P-type Silicon Doping – a few holes 5 © Unitec New Zealand

6. Summary of P & N Doping 6 © Unitec New Zealand

7. Combining to make P_N Junction 7 © Unitec New Zealand

8. P_N Zero Bias 8 © Unitec New Zealand

9. P_N Reverse Bias- wide depletion barrier 9 © Unitec New Zealand

10. P-N Forward Bias- thin depletion barrier 10 © Unitec New Zealand

11. P_N Diode Symbol & Characteristic I-V 11 © Unitec New Zealand

12. P-N Junction Diode Summary 12 © Unitec New Zealand

13. Diode Real vs Ideal Summary 13 © Unitec New Zealand

14. Small Signal Diodes 14 © Unitec New Zealand

15. Small Signal Diode V-I characteristic 15 © Unitec New Zealand

16. Small Signal Diode Summary 16 © Unitec New Zealand

17. Signal Diode Parameters 17 © Unitec New Zealand

18. Apps- Arrays and Data Line Protection 18 © Unitec New Zealand

19. Diodes in Series – simple Voltage Regulator 19 © Unitec New Zealand

20. Freewheel Diode – protect from Inductor 20 © Unitec New Zealand

21. POWER Diode – much larger PN junction Basic RECTIFIER 21 © Unitec New Zealand

22. Rectifier - simplest 22 © Unitec New Zealand

23. Half-Wave Smoothing Capacitor 23 © Unitec New Zealand

24. Full Wave Rectifier – special transformer 24 © Unitec New Zealand

25. Full wave BRIDGE Rectifier 25 © Unitec New Zealand

26. Bridge – POS & NEG cycle conduction 26 © Unitec New Zealand

27. Bridge Rectifier Modules Cutoff corner = +, opposite = -, other two wires= AC input 27 © Unitec New Zealand

28. Bridge Smoothing Capacitor 28 © Unitec New Zealand

29. ZENER Diodes – Voltage Regulators 29 © Unitec New Zealand

30. Reminder - Voltage divider formula 30 © Unitec New Zealand The ratio of individual resistance to total resistance is the same as the ratio of individual voltage drop to total supply voltage in a voltage divider circuit. This is known as the voltage divider formula

31. Voltage Regulator – for variable loads 31 © Unitec New Zealand

32. ZENER series Resistor Calculations 32 © Unitec New Zealand

33. ZENERs in series 33 © Unitec New Zealand

34. Typical ZENER voltages available 34 © Unitec New Zealand

35. Using ZENERs to CLIP sine-waves 35 © Unitec New Zealand

36. Using Normal Diodes to Clip Sine-waves 36 © Unitec New Zealand

37. BIASED Clipping 37 © Unitec New Zealand

38. PhotoVoltaic (PV) diode cell 38 © Unitec New Zealand

39. PV BYPASS Diodes –prevent backflow from other shaded PVs or full battery 39 © Unitec New Zealand

40. LED Characteristics 40 © Unitec New Zealand

41. LED needs series resistor to limit current 41 © Unitec New Zealand

42. Series LED strings 42 © Unitec New Zealand

43. Driving LEDs with ICs 43 © Unitec New Zealand

44. Driving LEDs with Transistors 44 © Unitec New Zealand

45. Driving LEDs with Pulse Width Modulation 45 © Unitec New Zealand

46. OPTO Coupler - ISOLATION 46 © Unitec New Zealand