Determine the minimum and the maximum input voltages that can be regulated by the zener diode.
1N4733A
Power Dissipation = 1.0 W
Vz= 5.1 V
Iz = 49 mA
Izk= 1 mA
Zz= 7Ω
Step 1:
5.1 V - ΔVz = 5.1 V - (49mA-1mA)7Ω
5.1 V - (.048mA)7Ω = 5.1V - .336V
Vout = 4.764 V
I am having trouble understanding exactly why we subtract the minimum zener current from test current and then multiply it by the zener impedance.
Why cant we just use 5.1 volts to find the Voltage input minimum and maximum?