Wednesday, 13 July 2016

What is Inside a 78xx series linear regulator IC / How a linear works?

A linear voltage regulator is basically a resistive voltage divider network.
A voltage divider divides voltages across the resistor. Here we can use a zener diode for voltage stabilization .  But It’s performance is not satisfactory.
Here is the most basic circuit

We used zener and the variable resistance for reference voltage and that we fed to the power transistor base which is in emitter follower configuration . current through the transistor proportional to base current applied.

Note: In this circuit a minimum load RL must be always connected.
Above regulator is quit simple but it’s voltage varies with load. So we need an feedback for adjusting the transistors base current.

Here is the final most practical circuit- 
More Details will be added in future