Zener Circuit

Question 1

In simple potential divider:

Answer 1

• Vo of simple potential divider will change if V changes
• Vo will also decrease if output is loaded by Rᶫ

Question 2

Zener Diode circuit:

Answer 2

• Diode with small defined breakdown voltage due to either Zener or Avalanche breakdown are all called Zener diode.
• Vo doesn’t change even if V changes (provided Iz between Izk<Iz<Izm)
• Vo = Vz even when loaded by Rᶫ (provided Iz between Izk<Iz<Izm)

Question 3

Load current, Iᶫ:

Answer 3

Iᶫ = Vz / Rᶫ (because Vo=Vz)

Question 4

Zener diode current, Iz, and Load current, Iᶫ

Answer 4

Iz + Iᶫ = (Vin - Vz)/R

Question 5

Maximum Vin

Answer 5

Vin = (Izm + Iᶫ)R + Vz

Question 6

Minimum Vin

Answer 6

Vin = (Izk + Iᶫ)R + Vz

Question 7

Izk

Answer 7

(Knee Current) minimum current to keep diode in breakdown region

Question 8

Izm

Answer 8

Maximum allowed Zener current