<Li> R must be large enough that the current through D does not destroy the device . If the current through D is I, its breakdown voltage V and its maximum power dissipation P correlate as such: I D V B <P max (\ displaystyle I_ (D) V_ (B) <P_ (\ text (max))). </Li> <P> A load may be placed across the diode in this reference circuit, and as long as the Zener stays in reverse breakdown, the diode provides a stable voltage source to the load . Zener diodes in this configuration are often used as stable references for more advanced voltage regulator circuits . </P> <P> Shunt regulators are simple, but the requirements that the ballast resistor be small enough to avoid excessive voltage drop during worst - case operation (low input voltage concurrent with high load current) tends to leave a lot of current flowing in the diode much of the time, making for a fairly wasteful regulator with high quiescent power dissipation, only suitable for smaller loads . </P> <P> These devices are also encountered, typically in series with a base - emitter junction, in transistor stages where selective choice of a device centered around the avalanche or Zener point can be used to introduce compensating temperature co-efficient balancing of the transistor p--n junction . An example of this kind of use would be a DC error amplifier used in a regulated power supply circuit feedback loop system . </P>

Explain how zener diode is used as a voltage regulator