Why do we need a voltage stabilizer

Fixed voltage regulator

At this point we will learn how we can generate regulated, i.e. constant voltages with simple ICs.

We use ICs that only have three connections and generate a fixed voltage.

It couldn't be much easier. We have an IC with an input to which a voltage is applied. A regulated voltage is made available at the output.

Both voltage sources have a common reference.

The capacitors at the input and output are necessary. They should be installed as close as possible to the voltage regulator IC.

The output voltage is specified by the IC. This is why these voltage regulators are called fixed voltage regulators.

Of course there are also adjustable voltage regulators.

A 3.3V regulator

We build a regulator with a 3.3V output voltage. The circuit is easy again.

We only replaced the voltage regulator with a concrete chip and specified the values ​​of the capacitors.

The capacitors C1 and C2 are electrolytic capacitors with the specified polarity, which must be observed.

The circuit can be operated from a voltage source from 4V.

There is an exact voltage of 3.3V (3.267V to 3.333V) at the output.

The LP2950 is supplied in a TO-92 package.

a - VO
b - GND
c - VI

We can strain the exit. We just use resistors for this.

We apply different resistances, measure the output voltage and calculate the current.

22Ω par. 22Ω
Short circuit

Short circuit? Is that possible?

Yes, the voltage regulator protects itself against overload.

We measure the short circuit current.

According to the data sheet, the LP2950 can be loaded with up to 100mA. The short-circuit current is a maximum of 220mA.

When the LP2950 is subjected to heavy loads, it heats up. It can get over 100 ° C. If it gets too hot, it will reduce the output current.

This behavior is common to most modern voltage regulators: