Consider a circuit given below: The cut in voltage of the diode
Consider a circuit given below:
The cut in voltage of the diode is 0.7 V and the breakdown voltage of the Zener diode is 2.7 V.
The correct transfer characteristics is ________
A. <img alt="" src="//storage.googleapis.com/tb-img/production/20/11/F1_Neha__7.11.20_Pallavi_D2.png" />
B. <img alt="" src="//storage.googleapis.com/tb-img/production/20/11/F1_Neha__7.11.20_Pallavi_D3.png" />
C. <img alt="" src="//storage.googleapis.com/tb-img/production/20/11/F1_Neha__7.11.20_Pallavi_D4.png" />
D. <img alt="" src="//storage.googleapis.com/tb-img/production/20/11/F1_Neha__7.11.20_Pallavi_D5.png" />
Please scroll down to see the correct answer and solution guide.
Right Answer is: C
SOLUTION
Case – I:
Let us assume initially that both Zener and diode are off
i.e. V0 = Vi and -0.7 < VI < 0.7
Case – II:
When Vi ≥ 0.7, the diode D2 is on but Zener is still off
\({V_0} = \left( {\frac{{{V_i} - 0.7}}{4}} \right) \times 2 + 0.7 = 0.5\;{V_i} + 0.35\)
Case III:
For the Zener to be in breakdown,
V0 = 2.7 V
To find the input at which Zener breaks down:
2.7 = 0.5 Vi + 0.35
Vi = 4.7 V
Case – IV
For Vi < 0.7 V, the Zener acts as a normal diode and the diode D2 is off
V0 = -0.7 V
∴ option 3 is correct answer.
