7809 IC Fixed Positive 9V Voltage Regulator
The LM7809 is a fixed positive voltage regulator that delivers a constant 9V output from a higher, unregulated DC input. It belongs to the standard 78xx series of three-terminal linear regulators, commonly used to power circuits that require a stable voltage source.
This IC operates with input voltages ranging typically from 11V to 25V, and can provide up to 1A of output current when used with an adequate heatsink. Internally, the device features a reference voltage, error amplifier, pass transistor, and thermal and current protection circuitry, ensuring reliable and safe voltage regulation under varying load and temperature conditions.
The LM7809 is ideal for applications where precise 9V output is needed, such as analog signal processing, audio circuits, microcontroller peripherals, and power supplies. Although it functions without additional components, using bypass capacitors on the input and output improves transient response and ripple rejection.
Pin Configuration (TO-220 Package)
| Pin | Name | Description |
|---|---|---|
| 1 | Input | Unregulated DC input |
| 2 | Ground | Common ground |
| 3 | Output | Regulated 9V output |
Applications
9V DC regulated power supply
Power for analog and audio circuits
Logic and microcontroller system supply
Sensor and module power conditioning
Battery-powered circuit regulation
DIY electronics and embedded projects
General-purpose voltage regulation
Key Features
Fixed and stable 9V output
Output current up to 1A
Input voltage range: 11V–25V
Thermal overload shutdown built-in
Short-circuit current protection
Current limiting for safety
Available in TO-220, TO-92, DPAK
Specifications Table
| Parameter | Value |
|---|---|
| Output Voltage | 9V ± 2% |
| Maximum Output Current | 1A (with heatsink) |
| Input Voltage Range | 11V to 25V |
| Dropout Voltage | 2V to 2.5V (typical) |
| Line Regulation | 4–100 mV (depending on current) |
| Load Regulation | 50 mV to 100 mV (typical) |
| Quiescent Current | 4–6 mA (typical) |
| Ripple Rejection | 60–80 dB (typical) |
| Operating Temperature Range | 0°C to +125°C |
| Junction Temperature Max | +150°C ‘ |
| Storage Temperature Range | −65°C to +150°C |
| Package Options | TO-220, TO-92, SOT-223, DPAK |
