LM7805 vs. LM7905

Attribute	LM7805	LM7905
Output Voltage	5V	-5V
Maximum Output Current	1A	1A
Input Voltage Range	7V-35V	-35V to -7V
Package Type	TO-220	TO-220
Thermal Shutdown	Yes	Yes

Introduction

When it comes to voltage regulation in electronic circuits, the LM7805 and LM7905 are two popular choices. These integrated circuits are part of the LM78xx series, which are fixed linear voltage regulators designed to provide a stable output voltage. While both the LM7805 and LM7905 serve the same basic function, there are some key differences between the two that make them suitable for different applications.

Output Voltage

The most obvious difference between the LM7805 and LM7905 is their output voltage. The LM7805 is a positive voltage regulator that provides a fixed output voltage of +5 volts, making it ideal for powering digital circuits and microcontrollers that require a stable 5V supply. On the other hand, the LM7905 is a negative voltage regulator that provides a fixed output voltage of -5 volts, which is useful for powering analog circuits and other components that require a negative supply voltage.

Current Rating

Another important factor to consider when choosing between the LM7805 and LM7905 is their current rating. The LM7805 is capable of delivering up to 1A of current, while the LM7905 has a slightly lower current rating of 0.5A. This means that the LM7805 is better suited for applications that require higher current output, such as driving multiple components or power-hungry devices.

Thermal Considerations

Both the LM7805 and LM7905 can generate heat during operation, especially when delivering high currents. To prevent overheating and ensure reliable performance, it is important to consider the thermal characteristics of these voltage regulators. The LM7805 comes in a TO-220 package with a built-in heat sink tab, which helps dissipate heat more effectively. On the other hand, the LM7905 also comes in a TO-220 package but may require an external heat sink for better thermal management.

Input Voltage Range

When selecting a voltage regulator for your circuit, it is essential to consider the input voltage range that the device can handle. The LM7805 has an input voltage range of 7V to 25V, which means it can accept a wide range of input voltages and still provide a stable 5V output. In comparison, the LM7905 has a narrower input voltage range of -25V to -7V, making it suitable for applications that require a negative supply voltage within this range.

Output Voltage Accuracy

Both the LM7805 and LM7905 are designed to provide a fixed output voltage with a high degree of accuracy. The LM7805 typically has an output voltage tolerance of +/- 5%, while the LM7905 has a similar tolerance of +/- 5%. This means that the actual output voltage of these regulators may vary slightly from the specified value, but the deviation is within an acceptable range for most applications.

Protection Features

When it comes to protecting your circuit from potential damage, the LM7805 and LM7905 offer some built-in protection features. Both regulators have overcurrent protection, which helps prevent damage to the device in case of a short circuit or excessive current draw. Additionally, the LM7805 and LM7905 have thermal shutdown protection, which shuts down the device if it exceeds a certain temperature to prevent overheating.

Conclusion

In conclusion, the LM7805 and LM7905 are both reliable voltage regulators that provide stable output voltages for a variety of electronic applications. While the LM7805 is better suited for applications that require a positive 5V supply and higher current output, the LM7905 is ideal for applications that require a negative 5V supply. By considering factors such as output voltage, current rating, thermal characteristics, input voltage range, output voltage accuracy, and protection features, you can choose the right voltage regulator for your specific needs.