Fixed Positive Voltage Regulators

This IC regulator provides a fixed positive output voltage. Although many types of IC regulators are available, the 7800 series of IC regulators is the most popular. The last two digits in the part number indicate the d.c. output voltage. For example [See Table below], the 7812 is a + 12V regulator whereas the 7805 is a + 5V regulator. Note that this series (7800 series) provides fixed regulated voltages from + 5 V to + 24V. Figure shows how the 7812 IC is connected to provide a fixed d.c. output of + 12V. The unregulated input voltage Vi is connected to the IC’s IN terminal and the IC’s OUT terminal provides + 12V. Capacitors, although not always necessary, are sometimes used on the input and output as shown in Figure. The output capacitor (C2) acts basically as a line filter to improve transient response. The input capacitor (C1) is used to prevent unwanted oscillations.