Description :
Voltage regulators are very common in electronic circuits. They provide a constant output voltage for a varied input voltage. In our case, the 7809 IC is an iconic regulator IC that finds its application in most of the projects. The name 7809 signifies two meanings, “78” means that it is a positive voltage regulator, and “09” means that it provides 9V as output. So our 7809 will provide a +9V output voltage.
The output current of this IC can go up to 1.5A. However, the IC suffers from heavy heat loss hence a Heatsink is recommended for projects that consume more current. For example, if the input voltage is 15V and you are consuming 1A, then (15-9) * 1 = 6W. This 6 Watts will be dissipated as heat.
Pin Description :
| Pin Number | Pin Name | Description |
| 1 | Input (V+) | Unregulated Input Voltage |
| 2 | Ground (GND) | Connected it to Ground |
| 3 | Output (Vo) | Outputs Regulated +9V |
Technical Specifications
| Physical | |
| Case/Package | TO |
| Mount | Through Hole |
| Number of Pins | 3 |
| Technical | |
| Accuracy | 2 % |
| Dropout Voltage | 2 V |
| Max Input Voltage | 35 V |
| Max Operating Temperature | 125 °C |
| Max Output Current | 1.5 A |
| Min Input Voltage | 11 V |
| Min Operating Temperature | -40 °C |
| Min Output Voltage | 9 V |
| Nominal Output Voltage | 9 V |
| Number of Channels | 1 |
| Number of Outputs | 1 |
| Number of Regulators | 1 |
| Output Configuration | Positive |
| Output Current | 1.5 A |
| Output Type | Fixed |
| Output Voltage | 9 V |
| Polarity | Positive |
| Power Supply Rejection Ratio (PSRR) | 55 dB |
| Quiescent Current | 8 mA |
| Tolerance | 5 % |
Brief Description of 7809 Voltage Regulator IC
Voltage regulators are very common in electronic circuits. They provide a constant output voltage for a varied input voltage. The name 7809 signifies two meanings, “78” means that it is a positive voltage regulator and “09” means that it provides 09V as output.
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.
L7809 as +9V Voltage Regulator
This is a typical application circuit of the 7809 IC. We just need two capacitors of value 0.33uf and 0.1uf to get this IC working. The input capacitor 0.33uF is a ceramic capacitor that deals with the 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 a ceramic type, since ceramic capacitors are faster than electrolytic.
7809 Applications
- Constant +9V 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
