The 7805 TO-252 is a three-terminal regulator with up TO 37V input and 5V output.
The three-terminal voltage regulator is generally used for the protection circuit of the direct current circuit, which plays the role of voltage reduction and voltage regulation.
Commonly used 78 series and 79 series, 78XX are positive voltage output, 79XX are negative voltage output, the input voltage is generally not too large, less than 36V.
78, 79 often appear after the L or H or blank to represent the rated current, such as 78L12 represents the output voltage of 12V 0.5A.
Wiring: When the word faces itself, the leftmost is 1 foot, the middle is 2 feet, and the rightmost is 3 feet. Pin 1 is connected to the voltage input, pin 2 is connected to the c terminal, and pin 3 is connected to the output terminal.