Design a Zener voltage regulator to meet the following specifications: Output voltage = 5 V, Load current = 10 mA, Zener wattage = 400 mW and Input voltage = 10 V ± 2 V.

Question

Accepted Answer

Given [latex]V_{0}[/latex] = 5 V, [latex]I_{L}[/latex] = 10 mA
Here, load resistance is [latex]R_{L} =\frac{V_{0}}{I_{L}}=\frac{5}{10 × 10^{– 3}}[/latex] = 500 Ω
Maximum Zener Current [latex]I_{z(max)} =\frac{400\,mW}{5\,V}[/latex] = 80 mA
The minimum input voltage required will be when [latex]I_{z}[/latex] = 0. Under this condition,
I = [latex]I_{L}[/latex] = 10 mA
Minimum input voltage [latex]V_{i(min)} = V_{o} [/latex] + IR
Hence, [latex]V_{i(min)}[/latex] = 10 – 2 = 8 V
or 8 = 5 + (10 × [latex]10^{– 3}[/latex]) R
Thererfore, [latex]R_{max} =\frac{3}{10 × 10^{– 3}}[/latex] = 300 Ω
Now, maximum input voltage, [latex]V_{i(max)} = 5 + [(80 + 10)10^{– 3}]R [/latex]
or 12 = 5 + (90 × [latex]10^{– 3}[/latex])R
[latex]R_{min} =\frac{7}{90 × 10^{– 3}}[/latex] = 77.77 Ω
The value of R is chosen between 77.77 Ω and 300 Ω.

Question 18.34: Design a Zener voltage regulator to meet the following speci...

Related Answered Questions