1© Unitec New Zealand
APTE 5601 &DE4401
SEMICONDUCTORSATOMIC STRUCTURE
DIODES
Conductors, Semiconductors, Insulators
2© Unitec New Zealand
Silicon Crystal Lattice- no free electrons
3© Unitec New Zealand
N-type Silicon Doping –few free electrons
4© Unitec New Zealand
P-type Silicon Doping – a few holes
5© Unitec New Zealand
Summary of P & N Doping
6© Unitec New Zealand
Combining to make P_N Junction
7© Unitec New Zealand
P_N Zero Bias
8© Unitec New Zealand
P_N Reverse Bias- wide depletion barrier
9© Unitec New Zealand
P-N Forward Bias- thin depletion barrier
10© Unitec New Zealand
P_N Diode Symbol & Characteristic I-V
11© Unitec New Zealand
P-N Junction Diode Summary
12© Unitec New Zealand
Diode Real vs Ideal Summary
13© Unitec New Zealand
Small Signal Diodes
14© Unitec New Zealand
Small Signal Diode V-I characteristic
15© Unitec New Zealand
Small Signal Diode Summary
16© Unitec New Zealand
Signal Diode Parameters
• Maximum Forward Current - else overheats
• Peak Inverse Voltage (PIV) - else breakdown
• Total Power Dissipation - in small fwd resistance
• Max Operating Temp – Junction Temp
17© Unitec New Zealand
Apps- Arrays and Data Line Protection
18© Unitec New Zealand
Diodes in Series – simple Voltage Regulator
19© Unitec New Zealand
Freewheel Diode – protect from Inductor
20© Unitec New Zealand
POWER Diode – much larger PN junction Basic RECTIFIER
21© Unitec New Zealand
Rectifier - simplest
22© Unitec New Zealand
Half-Wave Smoothing Capacitor
23© Unitec New Zealand
Full Wave Rectifier – special transformer
24© Unitec New Zealand
Full wave BRIDGE Rectifier
25© Unitec New Zealand
Bridge – POS & NEG cycle conduction
26© Unitec New Zealand
Bridge Rectifier Modules
• Cutoff corner = +, opposite = -, other two wires= AC input
27© Unitec New Zealand
Bridge Smoothing Capacitor
28© Unitec New Zealand
ZENER Diodes – Voltage Regulators
29© Unitec New Zealand
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
Voltage Regulator – for variable loads
31© Unitec New Zealand
ZENER series Resistor Calculations
32© Unitec New Zealand
ZENERs in series
33© Unitec New Zealand
Typical ZENER voltages available
34© Unitec New Zealand
Using ZENERs to CLIP sine-waves
35© Unitec New Zealand
Using Normal Diodes to Clip Sine-waves
36© Unitec New Zealand
BIASED Clipping
37© Unitec New Zealand
PhotoVoltaic (PV) diode cell
38© Unitec New Zealand
PV BYPASS Diodes –prevent backflow from other shaded PVs or full battery
39© Unitec New Zealand
LED Characteristics
40© Unitec New Zealand
LED needs series resistor to limit current
41© Unitec New Zealand
Series LED strings
42© Unitec New Zealand
Driving LEDs with ICs
43© Unitec New Zealand
Driving LEDs with Transistors
44© Unitec New Zealand
Driving LEDs with Pulse Width Modulation
45© Unitec New Zealand
OPTO Coupler - ISOLATION
46© Unitec New Zealand
Top Related