A LM7805 Voltage Regulator is a voltage regulator that outputs +5 volts.

An easy way to remember the voltage output by a LM78XX series of voltage regulators is the last two digits of the number. A LM7805 ends with “05”; thus, it outputs 5 volts. The “78” part is just the convention that the chip makers use to denote the series of regulators that output positive voltage. The other series of regulators, the LM79XX, is the series that outputs negative voltage. So:

LM78XX: Voltage regulators that output positive voltage, “XX”=voltage output.
LM79XX: Voltage regulators that output negative voltage, “XX”=voltage output

The LM7805, like most other regulators, is a three-pin IC.
Pin 1 (Input Pin): The Input pin is the pin that accepts the incoming DC voltage, which the voltage regulator will eventually regulate down to 5 volts.
Pin 2 (Ground): Ground pin establishes the ground for the regulator.
Pin 3 (Output Pin): The Output pin is the regulated 5 volts DC.

Pin Details of 7805 IC

Applications

7805 IC is used in a wide range of circuits. The major ones being:

• Fixed-Output Regulator
• Positive Regulator in Negative Configuration
• Adjustable Output Regulator
• Current Regulator
• Adjustable DC Voltage Regulator
• Regulated Dual-Supply
• Output Polarity-Reversal-Protection Circuit
• Reverse bias projection Circuit