# Understanding Voltage Regulator ICs

### Voltage Regulator IC - Tutorial:

To do the electrical projects most of the times, we have to convert AC into DC and then step down the 24 DC voltage in to lower voltage levels like 9V, 5V etc .
The circuit known as voltage regulator comes into picture at those moments.

#### What is meant by Voltage Regulator?

A Voltage Regulator is defined as an electronic circuit that provides a stable DC output voltage independent of the load current, temperature and AC line voltage variations.

• Voltage regulators can be usually built using opamp, Transistor, zener diode etc.
• But for low output voltage, current requirements, it is good to use voltage regulator ICs like 7805, 7812, 7808 , LM317 etc.
• It is quicker and easier to use regulator ICs.
• They are relatively inexpensive and we can programme the output voltage.
• In this post we will discuss some of the regulator ICs in detail.
• A simple fixed voltage regulator is shown in the above figure.
Refer the above figure. That 7805 IC. In that figure
Pin -1 = Input Voltage (7V – 35V)
Pin-2 =  Ground (0V)
Pin-3 =  Output Voltage (5V)

#### IC Voltage Regulators Types:

IC voltage regulators are classified as

1. Fixed Voltage Regulators
2. Variable Voltage Regulators
3. Dual Tracking Regulators

#### Three terminal Voltage Regulator IC:

• In these voltage regulators, the output voltage is set at some predetermined value.
• Depends on the requirement, the voltage regulators are available for the predetermined voltages like IC 7805, 7909, 7812 etc.
• Here the last two digits indicate the regulated output voltage.
• The 78XX series are three terminal positive fixed voltage regulators.
• In 78XX, the last two digits indicates the output voltage. ie 7805 means, that IC output voltage is 5V.
• In 78XX series seven voltage options are available like 5, 6, 8, 12, 15, 18 and 24.
• The 79XX series are three terminal negative fixed voltage regulators.
• In 79XX series nine voltage options are available like -2, -5, -5.2, -6, -8, -12, -15, -18 and -24.
• We can achieve adjustable output voltage from the voltage regulator ICs.

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