Question

A $7.2V$ zener diode $(7.2V$ at ${20}^{o}C)$ has a positive temperature coefficient of $0.0007{/}^{o}C$. What is the zener voltage at ${45}^{o}C$ ?

• A. $7.20V$
• B. $7.33V$
• C. $7.13V$
• D. $6.36V$

Answer 1

Answer: (B)

$7.33V$

Due to the positive temperature coefficient of zener diode, the increase in voltage of zener diode due to increase in temperature $=V_0\alpha \Delta \theta$
$=7.2\times 0.0007\times 25V=0.13V$

Hence, the zener voltage at temperature ${45}^{\circ }$ is $7.2V+0.13V=7.33V$