The LM7805 is a classic 3-terminal positive voltage regulator designed to provide a steady 5V output from a higher DC input voltage. It belongs to the 78xx family of fixed-voltage regulators and is widely used for providing local on-card regulation. The IC features internal current limiting, thermal shut-down protection, and safe-area compensation, making it virtually indestructible under normal operating conditions. It is the primary power source for millions of digital circuits, microcontrollers like the Arduino, and TTL logic gates, ensuring they receive a clean and stable voltage regardless of fluctuations in the input source.
LM7805 Pinout (TO-220)
In the common TO-220 package, with the part number facing you and the pins pointing down, the pinout is straightforward.
| Pin | Terminal | Function |
| 1 | Input (IN) | Unregulated DC voltage input (7V to 25V) |
| 2 | Ground (GND) | Connected to the circuit ground; also tied to the metal tab |
| 3 | Output (OUT) | Regulated +5V DC output |
Technical Specifications
- Output Voltage: 4.8V to 5.2V
- Input Voltage (VIN): 7V to 25V (Minimum 2V above output)
- Output Current: Up to 1.5A (with proper heatsinking)
- Peak Current: 2.2A
- Dropout Voltage: 2.0V (Typical)
- Operating Temperature: 0°C to 125°C
- Thermal Resistance: 5°C/W (Junction to case)
Key Features & Benefits
- Fixed Output: No external resistors are required to set the voltage.
- Thermal Overload Protection: Automatically shuts down if it becomes too hot.
- Short Circuit Protection: Limits the output current to prevent damage during a fault.
- High Stability: Provides a very clean output with very low ripple when used with capacitors.
Common Applications
- Logic Power Supplies: Powering 5V microcontrollers and digital logic circuits.
- Adjustable Output Regulators: Can be modified with external components for variable output.
- Battery Chargers: Providing a regulated voltage for charging 5V battery packs.
- DIY Power Supplies: A staple in lab bench power supply projects.
LM7805 Equivalent & Substitutes
- LM340-T5 (Direct equivalent)
- LM2596 (Switching regulator alternative for higher efficiency)
- L7805CV (Common variant from STMicroelectronics)
- UA7805 (Texas Instruments version)
Related Tutorials on ElxHub
- Basics: Learn more in Integrated Circuits – Basics and Working
- Selection Guide: Compare power options in our Ultimate IC Selection Guide
Conclusion
The LM7805 is an essential component for any electronics designer. Its simplicity and robust protection features make it the standard for 5V regulation. While modern switching regulators are more efficient for high-current tasks, the linear LM7805 remains the king of simplicity and noise-free operation for sensitive digital and analog systems.
Download the IC’s Datasheet pdf
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