Question

The 6.8 V zener diode in the circuit shown below is specified to have $V_Z=6.8V$ at $I_z=5mA{r}_z=0.2mAand{I}_{Zmin}=0.2mA.$ The supply voltage $V^{+}$ is nominally 10 V but can vary by $\pm$ 1 V.




the value of $V_0$ with no load and with $V^{+}$ at its nominal value is ________V.

• A. 6.83

Answer 1

The correct option is A 6.83
First we must determine the value of the parameter $V_{z0}$ of the Zener diode model
Substituting, $V_z$ = 6.8 V,
$I_z$ =5 mA
and $r_z$= 20 $\Omega$
yields, $V_{z0}$= 6.7 V


with no load connected the current through the zener is given by

$I_z=\frac{V^{+}-V_{z0}}{R+r_z}=\frac{10-6.7}{0.5+0.02}=6.35mA$

$V_0=V_{z0}+I_z{r}_z=6.7+6.35\times 0.02=6.83V$