L78L05ACD13TR Detailed explanation of pin function specifications and circuit principle instructions
The part number L 78L05 ACD13TR is an integrated circuit, specifically a Voltage Regulator manufactured by STMicroelectronics. It is part of the L78 series of voltage regulators. This particular model is a Low Dropout Regulator (LDO) with a fixed output voltage of 5V. It comes in a TO-220 package and is commonly used for power supply circuits that require a stable 5V output from higher input voltages.
Pin Function Specifications & Detailed Circuit Explanation
Package Type: TO-220
The TO-220 package is a 5-pin package widely used for power regulators and transistor s. Pin Count: 5 pins (L78L05ACD13TR)Below is the detailed function for each pin of the L78L05ACD13TR in the TO-220 package:
Pin Number Pin Name Function Description 1 Input (Pin 1) Input Pin (V_in): This is where the unregulated DC voltage (usually higher than 5V) is applied. The input voltage range is typically 7V to 35V. This pin is connected to the power supply providing the higher voltage. 2 Ground (Pin 2) Ground Pin (GND): This is the ground or negative pin of the regulator, typically connected to the circuit’s common ground. 3 Output (Pin 3) Output Pin (V_out): This pin provides the regulated 5V output. The output voltage is stable around 5V, as per the regulator's specifications. 4 N/C (Pin 4) No Connection (N/C): This pin is not connected internally and serves no purpose in the functionality of the L78L05ACD13TR. It is typically left unconnected in the circuit. 5 N/C (Pin 5) No Connection (N/C): Like Pin 4, this pin is also not connected internally and does not affect the operation of the regulator.Circuit Principle of the L78L05ACD13TR
The L78L05ACD13TR is a low dropout regulator. It operates by taking the input voltage (higher than 5V) and providing a stable 5V output (with a low difference between input and output voltages).
Dropout voltage: The L78L05ACD13TR has a very low dropout voltage, meaning that the input voltage needs to be only slightly higher than the output voltage for the regulator to maintain its 5V output. This makes it efficient for applications where space and power consumption are critical. Internal Protection: The L78L05ACD13TR includes internal thermal shutdown, current limiting, and safe-area control to protect both the device and the circuit.Frequently Asked Questions (FAQ)
1. What is the input voltage range for the L78L05ACD13TR? The input voltage range is 7V to 35V, but the input voltage must always be higher than 5V by at least the dropout voltage for proper regulation. 2. What is the output voltage of the L78L05ACD13TR? The output voltage is 5V. It is a fixed voltage regulator. 3. What is the current output rating of the L78L05ACD13TR? The maximum output current is typically 500mA. 4. What package does the L78L05ACD13TR come in? The L78L05ACD13TR comes in a TO-220 package. 5. What is the dropout voltage of the L78L05ACD13TR? The dropout voltage is typically 1.5V, meaning the input voltage must be at least 1.5V higher than the output for proper regulation. 6. What are the pin connections for the L78L05ACD13TR? The L78L05ACD13TR has 5 pins: Input (Pin 1), Ground (Pin 2), Output (Pin 3), N/C (Pin 4), and N/C (Pin 5). 7. Can the L78L05ACD13TR be used in battery-powered circuits? Yes, it can be used, but ensure that the input voltage is within the specified range of 7V to 35V. 8. What happens if the input voltage falls below 7V? The regulator will no longer function properly, and the output voltage will drop below the regulated 5V level. 9. How does the L78L05ACD13TR provide thermal protection? The L78L05ACD13TR includes thermal shutdown which turns off the regulator if it overheats to protect the device from damage. 10. Can I use the L78L05ACD13TR in high-frequency applications? The L78L05ACD13TR is designed for low-frequency applications and may not perform well in high-frequency circuits due to its internal architecture. 11. Can the L78L05ACD13TR be used with capacitor s? Yes, the L78L05ACD13TR typically requires input and output capacitors to ensure stability. Recommended values are 0.33µF at the input and 0.1µF at the output. 12. What is the function of the N/C pins (Pins 4 and 5)? The N/C pins are not connected internally and serve no function in the operation of the L78L05ACD13TR. 13. What is the typical efficiency of the L78L05ACD13TR? The typical efficiency is relatively low because it is a linear regulator. Efficiency can be calculated as ( \text{Efficiency} = \frac{V{out}}{V{in}} \times 100\% ). 14. Can the L78L05ACD13TR be used in conjunction with a heat sink? Yes, if the regulator is used at high currents or voltages, it may require a heat sink to dissipate heat effectively. 15. Is the L78L05ACD13TR suitable for automotive applications? Yes, the L78L05ACD13TR can be used in automotive applications if the input voltage is within the specified range and proper filtering is used to protect against voltage spikes. 16. What happens if the load current exceeds the maximum rating of 500mA? If the load current exceeds 500mA, the regulator will enter current limiting mode, potentially resulting in reduced output voltage or thermal shutdown to protect the device. 17. What is the typical dropout voltage of the L78L05ACD13TR? The typical dropout voltage is 1.5V, but this can vary slightly depending on the load current. 18. What is the output voltage tolerance of the L78L05ACD13TR? The output voltage tolerance is typically ±2% at room temperature. 19. Can I use the L78L05ACD13TR without external capacitors? While the L78L05ACD13TR may operate without external capacitors, it is recommended to use them for better stability and transient response. 20. What is the purpose of the ground pin (Pin 2) in the L78L05ACD13TR? The ground pin (Pin 2) connects the regulator to the circuit's common ground and is essential for proper operation of the voltage regulator.This detailed explanation includes the pinout, usage guidelines, and frequently asked questions for the L78L05ACD13TR voltage regulator.
