Zener Diode

I am starting a series of electronics devices theory for students and my first topic is Zener diode. 

Zener diode:

Zener diode is two terminal device and have one PN highly doped junction use for voltage regulation in reverse bias to parallel at input of device or at output of DC power supply.

Physical shape: 

Symbol:

Characteristic (V-I) curve:

Forward bias:

when we connect anode with + terminal of the battery and cathode with - terminal of the battery then current flow start anode to cathode after 0.7 junction volt as shown in V-I curve.

Reverse bias:

When we apply cathode with + terminal and anode with - terminal then after zener voltage diode will start conduction in reverse bias (its called Zener break down).

When voltage more increase then a lot of current flow through zener diode and diode will burn out (its called avalanche break down) as shown in V-I curve.  

Load Regulation:

This is very simple science fixed input voltage and load is variable

load current increase:

when load current increase the zener current decrease and extra voltage drop across R1  and output voltage remain same.

Load current decrease:

when load current decrease then zener current increase and voltage at output remain same. and total current remain same.(will see one more post with solve examples)

Line Regulation:

In line regulation Vin (Line voltage) are variable and load is at fixed value.

Vin increase:

when input voltage increase then load voltage remain constant according to zener voltage and remaining Max voltage drop across R1.

Vin decrease but > Vz:

when vin decrease then Vz and load voltage also remain constant due to conduction of zener diode and renaming min voltage drop across R1.

Vin < Vz:

when Vin decrease then Vz then applied divide at R1 and RL. (No need this case) 

lecture watch on YouTube: