help Field scenario: The zener diode was tested and found to be shorted. The lim

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Field scenario: The zener diode was tested and found to be shorted. The limiting resistor has opened, we are not concerned with the cause of the failure. The failure could be on the load side, supply side, or just zener failure. We will concern ourselves with replacing the zener and limiting resistor in this example. Calculate the limiting resistor and the power rating needed to protect the circuit again. Use the Parameters based from the test current and zener max current from the above data sheet Information. Please show all work for credit. Calculate the minimum and maximum input voltage to keep the zener in regulation. What would be the lowest load resistor the zener can handle and stayjn Regulation.

Explanation / Answer

1) at test

Vz = 24V

Iz = 10.5mA

Il is load current

Po=1W =Vz*Il

Iz=41.67mA

Iz(max)=38mA

Max current through Rlimit= 41.67+38=79.67mA

Max voltage across Rlimit when supply is shorted

Vmax=24V

Rlimit = (24/79.67) =301.25ohm

Power rated = 24*79.67=1.9W

2)Vmin =24V

Vmax= 24 + Imax*Rlimit = 24+ (24) =48V

3) Maximum current through Rlimit = 79.67mA

so Ilmax = 79.67 - 10.5 =69.17mA

R=V/I = 24/69.17 =347ohm

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