What is 7805 Voltage Regulator & Its Working

For every electronic device, the regulated power supply is essential because these devices use semiconductor material with a fixed rate of voltage and current. If there is any difference in the fixed rate of voltage and current, then the device will get damage. Batteries are one of the main DC supply sources but we cannot use battery over time in sensitive electronic circuits as they lose their potential & drain out ultimately. The batteries provide different voltage ranges like 1.2 Volts, 3.7 Volts, 9 Volts, and 12 Volts. Most of the integrated circuits work with 5V supply therefore we require a device to supply a reliable 5V Supply called voltage regulator. Here, a 7805 voltage regulator comes from 78XX series of the linear voltage regulators. This regulator generates 5V regulated output.

What is a Voltage Regulator?

The voltage regulator is one kind of electrical component used to maintain a stable voltage across any electronic device. The fluctuations in the voltage can cause an undesirable cause in an electronic system. For that, maintaining a stable voltage is compulsory based on the system voltage requirement.

For instance, a simple LED uses a maximum of 3V. Once the voltage increases than this voltage, then the diode will get damage. Similarly, in all the electrical and electronic components, it is common. Once the voltage increases, all the components in the system will get damaged. To overcome this situation, a voltage regulator is used to provide a regulated power supply.

What is the 7805 Voltage Regulator?

Definition: IC 7805 is a linear voltage regulator and it includes three terminals including 5V of the fixed output voltage. This voltage is used in a variety of applications. At present, the manufacturing of this voltage regulator can be done by different manufacturing companies like STMicroelectronics, ON Semiconductor, Texas Instruments, Infineon Technologies, Diodes incorporated, etc. These ICs are available in different packages namely TO-3, TO-220, TO-263, and SOT-223. But the most frequently used package is TO-220.

The equivalent ICs of this voltage regulator are IC LM7809, IC LM7806, IC LM317, IC LM7905, IC XC6206P332MR & IC LM117V33.


The main features of the IC 7805 voltage regulator include t following.


  • It uses fewer components to work properly.
  • It delivers the current up to 1.5 A.
  • Thermal shut down & internal current limiting.
  • Minimum & maximum input voltages are 7V & 25V.
  • The operating current is 5mA.
  • Protection of short circuit and thermal overload.
  • The highest junction temperature is 125 degrees Celsius.
  • It is available in KTE and TO-220 package.

Pin Diagram

The pin diagram of the 7805 voltage regulator is discussed below. This voltage regulator includes three pins namely input pin, ground pin, and output pin. Each pin and its function can be discussed below.

7805 Voltage Regulator Pin Diagram
7805 Voltage Regulator Pin Diagram
  • Pin1 (Input): This is an input pin, where a positive unregulated voltage can be given like an input toward this pin.
  • Pin2 (Ground): This is the GND pin where this pin is common to both input & output.
  • Pin3 (Output): This is the output pin where the 5V of regulated voltage can be taken at this pin.

7805 Voltage Regulator Circuit

The circuit diagram of the 7805 voltage regulator is shown below. This circuit generates a 5V regulated supply from AC mains. This circuit can built with a step-down transformer (230V-12V), bridge rectifier, Fuse 1A, Capacitor-1000μF, IC 7805-voltage regulator, capacitors- 0.22μF & 0.1μF, diode 1N4007.

7805 Voltage Regulator Circuit
7805 Voltage Regulator Circuit

IC 7805 Voltage Regulator Working

In the above circuit, the AC power supply is converted into DC. This circuit is designed with a transformer, a bridge rectifier, IC 7805linear voltage regulator otherwise capacitors.

This circuit is divided into two portions wherein the first portion of the circuit, the AC mains can be changed into DC. In the second portion, this DC can be changed into regulated 5V DC. At first, a step-down transformer is used to step down the voltage from 230V to 12V by connecting its primary winding to the mains supply. The secondary winding of the transformer can be connected to bridge rectifier

A 1A fuse is arranged in between the bridge rectifier and the transformer to stop the flow of current that is drawn through the 1A circuit. The bridge rectifier generates a rectified DC that is smoothened using 1000μF Capacitor. So, the output of the 1000μF capacitor is 12V unregulated DC. This DC can be given used like an input to the IC 7805 voltage regulator. After that, this regulator changes regulated 5V DC & the o/p is attained at its o/p terminals.

In the above circuit, the input voltage must be higher compare with the o/p voltage. The I/O currents are nearly the same. Once the 7.5V 1A supply can be given at i/p, then the o/p will be 5V 1A. The residual power can be dissipated like heat using the 7805 IC.

Heat Dissipation in IC 7805

In this kind of regulator, huge energy can be exhausted in heat form. The disparity in the input & output voltage will generate heat. So, if the difference in the voltage is high, then there will be a high generation of heat. So a heat sink is used with IC 7805 otherwise surplus heat will be the reason for malfunction.


The advantages of the IC 7805 voltage regulator include the following.

  • This does not need any component to handle its output voltage.
  • In includes built-in protection to protect from the overvoltage.
  • A heat sink can be used through the GND terminal to protect the IC from high current or short circuits.

7805 Voltage Regulator Applications

The applications of 7805IC include in a wide range of electrical and electronic circuits like the following.

  • Changeable Output Regulator
  • Permanent O/P Regulator
  • Current Regulator
  • DC Voltage Regulator
  • Reverse Bias based Projection Circuit
  • Inductance Meter
  • Phone Charger
  • Portable CD Player
  • Extension of IR remote control
  • UPS power supply circuits.
  • Used as +5V voltage regulator

Thus, this is all about an overview of the 7805 voltage regulator. These are used in various electronic circuits to provide a stable o/p voltage for a different i/p voltage. So this IC can be used in most of the electronic projects. In this IC, 78 signifies a +ve voltage regulator whereas 05 signifies 5V output voltage. So this IC will provide +5V as an output voltage. Here is a question for you, what are the different types of voltage regulators?

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