LM7805 vs LM317: Which Voltage Regulator to Use for Your Project

When embarking on an electronics project, choosing the right components is crucial for ensuring efficiency and functionality. Voltage regulators are integral parts of many circuits, particularly when dealing with microcontrollers like Arduino or powering motors. Two popular voltage regulators are the LM7805 and the LM317. This blog post will explore the differences between these regulators and guide you on which to use for various projects, including motor drivers, Arduino setups, and drone electronics.

 

LM7805 Voltage Regulator

The LM7805 is a fixed voltage regulator that provides a stable 5V output from a higher voltage input (typically between 7V and 35V). Here are its key features:

1. Fixed Output Voltage: Delivers a constant 5V output.
2. Easy to Use: Requires minimal external components (just a couple of capacitors for stability).
3. Current Capacity: Typically handles up to 1.5A of current, making it suitable for many low-power applications.
4. Thermal and Overcurrent Protection: Built-in protection features enhance reliability and safety.

LM317 Voltage Regulator

The LM317 is an adjustable voltage regulator that can provide an output voltage range of 1.25V to 37V with the appropriate external resistors. Here are its key features:

1. Adjustable Output Voltage: Allows for a wide range of output voltages.
2. Versatility: Can be used in various applications due to its adjustable nature.
3. Current Capacity: Similar to the LM7805, it can handle up to 1.5A of current.
4. Thermal and Overcurrent Protection: Like the LM7805, it has built-in protection features.

See for example design of 12V voltage regulator using LM317.

Choosing the Right Regulator for Your Project

1. Motor Driver + Arduino Project

For a motor driver and Arduino project, the choice of voltage regulator depends on the specific requirements of your setup:

• LM7805: If your Arduino operates at 5V and your motor driver can also work within the same voltage range, the LM7805 is a straightforward choice. It simplifies the design by providing a stable 5V supply directly.
• LM317: If you need different voltage levels for your Arduino and motor driver, the LM317 voltage regulator offers flexibility. For example, you might use 5V for the Arduino and a different voltage for the motor driver.

Recommendation: Generally, the LM7805 is easier to implement for most Arduino and motor driver projects that require a 5V supply. If flexibility is needed, consider the LM317.

2. Drone Electronics

Drones often have more complex power requirements due to multiple components like flight controllers, ESCs, cameras, and sensors. Here's how each regulator fits in:

• LM7805: Suitable if you have components that require a stable 5V supply. However, drones typically need more flexibility in voltage regulation.
• LM317: Provides the necessary versatility to regulate various voltages required by different drone components.

Recommendation: The LM317 is usually a better fit for drone electronics due to its adjustable output, allowing you to tailor the voltage to specific components.

3. Other Types of Projects

• Fixed Voltage Requirements: For projects that require a constant 5V supply, the LM7805 is ideal due to its simplicity and ease of use.
• Variable Voltage Requirements: For projects needing multiple or varying voltage levels, the LM317 is the better choice. Its adjustability can accommodate a wide range of applications.

Conclusion

Both the LM7805 and LM317 voltage regulators have their advantages, and the best choice depends on your specific project requirements:

• Use the LM7805 for straightforward applications requiring a stable 5V output, such as simple Arduino projects.
• Use the LM317 for more complex applications needing adjustable output voltages, such as drone electronics or projects with varying voltage needs.
  

By understanding the characteristics and capabilities of these regulators, you can make an informed decision to ensure the success and efficiency of your electronics projects. See also How automatic cutoff battery charger circuit works which shows how to design voltage regulator without any voltage regulator IC.