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Physical electronics devices and ics miscellaneous

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Physical Electronics Devices and ICs

Physical electronics devices and ics miscellaneous
  1. A Zener diode regulator shown in the figure given below is to be designed to meet the following specifications—
    IL = 10 mA, V0 = 10 V, Vin varies from 30 V to 50 V. The zener diode has VZ = 10 V and IZK (knee current) = 1 mA. For satisfactory operation, which one of the following is correct?


    1. R 1800 Ω
    2. 2000 Ω R 2200 Ω
    3. 3700 Ω R 4000 Ω
    4. R > 4000 Ω
Correct Option: A

The given circuit (i.e., fig)
Given, V0 = VZ = 10V
IL = 10 mA
IZK (Knee current) = 1 mA
30V ≤ Vi ≤ 50V
From figure IR(min) = Vi(min) – VZ R
R ≤ Vi(min) – VZ IZK + IL
or R ≤ 30 – 10 1 mA + 10 mA
or R ≤ 1818Ω
Hence alternative (A) is the correct choice.


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