Brief Description of 7805 Voltage Regulator IC

Voltage regulators are very common in electronic circuits. They provide a constant output voltage for a varied input voltage. In our case the 7805 IC is an iconic regulator IC that finds its application in most of the projects. The name 7805 signifies two meaning, “78” means that it is a positive voltage regulator and “05” means that it provides 5V as output. So our 7805 will provide a +5V output voltage.

The output current of this IC can go up to 1.5A. But, the IC suffers from heavy heat loss hence a Heat sink is recommended for projects that consume more current. For example if the input voltage is 12V and you are consuming 1A, then (12-5) * 1 = 7W. This 7 Watts will be dissipated as heat. 

7805 as +5V Voltage Regulator

This is a typical application circuit of the 7805 IC. We just need two capacitors of vale 33uf and 0.1uf to get this IC working.

The input capacitor 0.33uF is a ceramic capacitor that deals with input inductance problem and the output capacitor 0.1uF is also a ceramic capacitor that adds to the stability of the circuit. These capacitors should be placed close to the terminals for them to work effectively. Also they should be of ceramic type, since ceramic capacitors are faster than electrolytic.

7805 as adjustable output Regulator

This IC can also act as an adjustable output voltage regulator, meaning you can also control the output voltage for your desired value using the below circuit.

Here, the input voltage can be anywhere between 9V-25V, and the output voltage can be adjusted using the value of resistance R1 and R2. The value can be calculated using the below formulae.

Where, Vxx=5, IQ = 5*10-3

7805 Applications

• Constant +5V output regulator to power microcontrollers and sensors in most of the projects
• Adjustable Output Regulator
• Current Limiter for certain applications
• Regulated Dual Supply
• Output Polarity-Reversal-Protection Circuit

2D model