For what range Vs will workSolutionThe property of zener dio

Solution

The property of zener diode is it will conduct in reverse bias direction and also acts as voltage regulator

The source voltage v_S must be greater than 12 plus the drop across 1.0 K resistor.

The current through 6.3 K resistor is given by 12/6.3k = 1.904mA

The maximum current through zener diode is 30mA and minimum current is 5mA. So we will take these two cases separately for finding the limits of source voltage

When I_Z = 5 mA

Apply KCL. If source current is sum of current on diode and load resistance

Source current is 5+1.904= 6.904 mA

Voltage drop across source resistance is 6.904 * 1 = 6.904V

Apply KVL input source voltage is 12+6.904 = 18.904V

When I_Z = 30mA

Apply KCL. If source current is sum of current on diode and load resistance

Source current is 30+1.904= 31.904 mA

Voltage drop across source resistance is 31.904 * 1 = 31.904V

Apply KVL input source voltage is 12+31.904 = 43.904V

So the range of input voltage is (18.904,43.904)