Question 222: Semiconductors and Logic Gates

Question

A zener of breakdown voltage V
z
= 8 V and maximum zener current, I
ZM
= 10 mA is subjectd to an input voltage V
i
= 10 V with series resistance R = 100 $\Omega$. In the given circuit R
L
represents the variable load resistance. The ratio of maximum and minimum value of R
L
is _____________.
![](https://app-content.cdn.examgoal.net/fly/@width/image/1l57dan5o/fb23e2d1-3fd7-4ac9-95bd-81b61ecc109c/2e0e88b0-fbf0-11ec-a838-9d46935e6482/file-1l57dan5p.png?format=png)

Accepted Answer

Minimum value of R
L
for which the diode is shorted is ${{{R_L}} \over {{R_L} + 100}} 	imes 10 = 8 \Rightarrow {R_L} = 400\,\Omega $
For maximum value of R
L
, current through diode is 10 mA
So ${i_R} = {i_{{R_L}}} + {I_{ZM}}$
${2 \over {100}} = {8 \over {{R_L}}} + 10 	imes {10^{ - 3}}$
$10 	imes {10^{ - 3}} = {8 \over {{R_L}}}$
${R_L} = 800\,\Omega $
So ${{{R_{L\,\max }}} \over {{R_{L\,\min }}}} = 2$

Semiconductors and Logic Gates

A zener of breakdown voltage V z = 8 V and maximum zener current, I ZM = 10 mA is subjectd to an input voltage V i = 10 V with series resistance R = 100 \Omega. In the given circuit R L represents the variable load resistance. The ratio of maximum and minimum value of R L is _____________.

Integer / Numeric Answer Type