Zener Diodes Homework: Load Regulation

[exis]

Homework Statement

A designer requires a shunt regulator of approximately 20V. two kinds of zener diodes are available: 6.8V devices with r_z=10ohms and 5.1V devices with r_z=30ohms. For the two major choices possible, find the load regulation. In this calculation neglect the effect of the regulator resistance R.

The Attempt at a Solution

For the first type of zener diode i figured that 3 of them would provide 20.4V with 30ohms resistance. For the 5.1 zeners, using 4 diodes to provide 20.V with 4*30=120ohm resistance would also do the trick. What I'm having trouble with is finding the load regulation which according to my solution manual should be -30mV/mA and -120mV/mA.

 

[Redbelly98]

I guess I'd have to see a circuit schematic to see what is going on, and perhaps an explicit definition of load regulation as well. I do notice that the load regulation is simply -R for each Zener combination.

 

[Mene]

I would like to clarify that the load regulation is a measure of how well a voltage regulator maintains a constant output voltage as the load changes. It is typically expressed as a percentage change in output voltage per unit change in load current. In this case, it is not clear what the load current is, so it is difficult to accurately calculate the load regulation for these zener diodes.

However, I can provide some general information about load regulation for zener diodes. Zener diodes have a characteristic curve that shows the relationship between the zener voltage and the zener current. This curve is typically very steep near the desired zener voltage, and becomes much flatter at higher currents. This means that a small change in current can result in a large change in voltage near the desired zener voltage, but a larger change in current is needed to produce the same change in voltage at higher currents.

In this case, the load regulation would depend on the specific load current and the characteristics of the zener diodes being used. It is possible that the 6.8V zener diodes with a lower resistance would have a better load regulation than the 5.1V zener diodes with a higher resistance, but it would also depend on the specific values of the load current and the regulator resistance.

In order to accurately calculate the load regulation, more information would be needed, such as the specific values of the load current and the regulator resistance, as well as the characteristics of the zener diodes being used. Without this information, it is not possible to accurately determine the load regulation for these zener diodes.