Two-terminal fixed positive voltage regulator

Commonly used three-terminal fixed positive voltage regulators include the LM780 series, LM78L00 series and LM78M00 series, collectively referred to as the 7800 series regulators. The difference between them is the maximum output current, and their circuit structures are basically the same. Figure 1 shows the external shape of the 7800 series three-terminal fixed voltage regulator, where pin 1 is the input terminal, pin 2 is the output terminal, and pin 3 is the reference voltage terminal. Grounding pin 3 can obtain a positive voltage output at the output terminal that is common to the input terminal. The typical application circuit is shown in Figure 2.

Figure 1 External pinout of the 7800 series three-terminal fixed positive voltage regulator

a) Form 1 b) Form 2 c) Form 3

Figure 2 Typical application circuit of 7800 series three-terminal fixed positive voltage regulator