Zener Diode It is an electronic component that

Zener Diode : It is an electronic component that allows current to pass through one direction only.

Zener Diode : A Zener diode allows current to flow from its anode to its cathode like a normal semiconductor diode, but it also permits current to flo in the reverse direction at specific reverse voltage , this is called as Zener voltage. If we increase the reverse voltage beyond zener vo the current through it increases rapidly but voltage remains consta This property of zener diode in reverse bias is used for voltage stabilisation. Zener diode is basically heavily doped pn juction diod

Voltage Regulator Voltage means potential difference between two points whereas regulator m to control or maintain. Hence voltage regulator is an electronic component or circuit that controls or maintains the voltage constant across the terminals. Where is it used? Most of the electronic devices work on DC supply whereas the voltage available is in the form of AC, hence we convert AC into DC. During conversion there can be small ripples or change in input line voltage[change in input will change output] load current[ increse the voltage drop across internal resistance] which will lead to change in output voltage. And hence to avoid this we use zener

Power Supply Power supply is a device that is used to convert AC into regulated DC. 1. 2. 3. 4. Transformer: It is used to step down the voltage Rectifier: It converts bi directional current into unidirectional current. Filter: It is used to reduce the ripples Regulator: It is used to eliminate ripples and give a constant DC.

Zener diode as voltage regulator As shown in the figure above zener diode is connected in reverse bias. We also join the resister in series to limit current through zener diode so that current lies between Iz max and Iz min Unregulated voltage should be sufficiently higher than zener voltage in order to obtain good regulation, however if the voltage is lower than zener voltage then diode will be off and output voltage will drop.

Zener diode as voltage regulator I= Iz + IL {by KCL} Vi= IR + Iz. Rz {by KVL} Iz. Rz = Vi - IR I = [Vi – Vz] / R There are two cases when output voltage will try to change: 1. With variation in supply voltage Vi, the total current will vary and correspondingly the zener current Iz adjust itselfby keeping load current IL constant. 2. With variation in load resistance RL the load current IL, will change but again the value of zener current Iz adjust itself so that Vz will remain constant, that means output voltage will remain constant. Question: V directly proportional to R? The zener diode here works like spring, it tries to regain the constant voltage just like stretched or compressed spring tries to regain its original length.