current limiter circuit diagram

Description: The LM117/LM317 from National Semiconductor Corporation is a three-terminal adjustable positive voltage regulator integrated circuit (IC). The output voltage range of the LM117/LM317 is from 1.2V to 37V with a load current capability of up to 1.5A. It is straightforward to use, requiring only two external resistors to set the output voltage. Additionally, it offers better line and load regulation compared to standard fixed regulators. The LM117/LM317 includes built-in overload protection and safe area protection circuits. Typically, no external capacitor is required unless the input filter capacitor is more than 6 inches (15 cm) away from the LM117/LM317. The transient response can vary with the output capacitor, and adjusting the filter capacitor can enhance ripple rejection compared to standard three-terminal regulators. The LM117/LM317 can be utilized for various specialized applications, such as adjusting the voltage for high voltage systems, as long as the input and output voltage differential does not exceed the specified limits. It is essential to avoid output short circuits. The output voltage can be programmed to a specific value, with a minimum adjustable output voltage of 1.2V and a guaranteed output current of 1.5A. The typical line regulation is 0.01%, and the load regulation is 0.1%, with a ripple rejection ratio of 80dB. The device features output short circuit protection, overcurrent protection, and thermal overload protection. It operates within a safe thermal range, with a maximum input-output voltage differential of 40V. The LM317's maximum input voltage is 30V, and it can provide an output voltage range of 1.5V to 32V at 1.5A, while also requiring attention to power consumption and heat dissipation. The LM317 has three pins: an input pin for the positive voltage, an output pin connected to the load, and a voltage adjust pin connected to a resistor and a variable resistor grounded. Input and output filter capacitors should also be connected to ground.

The LM117/LM317 voltage regulator is designed to provide a highly stable output voltage while accommodating a variety of load conditions. The adjustable output voltage is achieved through the use of two external resistors, which form a voltage divider that sets the desired output level. The internal architecture of the LM117/LM317 includes a feedback mechanism that continuously monitors the output voltage and adjusts it as necessary to maintain the set level, ensuring precision regulation across varying load currents.

In applications where the distance between the regulator and the load is significant, the requirement for an input capacitor becomes crucial. This capacitor aids in filtering any high-frequency noise that may affect the performance of the regulator, particularly in sensitive electronic circuits. The transient response of the regulator can be optimized by selecting appropriate output capacitors, which can help to further reduce voltage fluctuations during rapid load changes.

The LM117/LM317 is particularly useful in power supply circuits where adjustable voltage levels are necessary, such as in laboratory power supplies, battery chargers, and various electronic devices requiring a stable voltage source. Its protection features, including thermal shutdown and current limiting, enhance the reliability of the circuit, preventing damage under fault conditions.

Moreover, the device's compact three-terminal package allows for easy integration into circuit designs, making it a popular choice among engineers. The versatility of the LM117/LM317 extends to applications in LED drivers, where it can be configured as a constant current source, ensuring that LEDs receive a stable current for optimal brightness and longevity.

In summary, the LM117/LM317 voltage regulator is a robust solution for applications requiring adjustable voltage regulation, characterized by its ease of use, protective features, and adaptability to various electronic circuit designs.LM117/LM317 National Semiconductor Corporation is a three-terminal adjustable positive voltage regulator ICs. LM117/LM317 output voltage range is 1. 2V to 37V, load current up to 1. 5A. It`s very simple to use, only two external resistors to set the output voltage. Besides its line regulation and load regulation than standard fixed regulators good. LM117/LM317 built-in overload protection and safe area protection and other protective circuits. Usually LM117/LM317 no external capacitor, unless the input filter capacitor to the input connection LM117/LM317 more than 6 inches (15 cm). Transient response can change with the output capacitor. Adjust the filter capacitor can be used side than the standard three-terminal regulator with high ripple rejection and more.

LM117/LM317 to have many special uses. Such as adjusting the suspension to end on a high voltage can be used to adjust the voltage up to several hundred volts, as long as the input and output pressure of not more than LM117/LM317 limit on the line. Of course, to avoid output short circuit. It can also be adjusted end to a programmable voltage, programmable power output. Adjustable output voltage as low as 1. 2V. Ensure 1. 5A output current. A typical line regulation of 0. 01%. 0. 1% typical load regulation. 80dB ripple rejection ratio. Output short circuit protection. Overcurrent and overheating protection. Adjust the tube safe operating area protection. Standard three-terminal transistor package. Symbol Parameter Value Unit VI-O Input - Output voltage differential output current is internally limited 40VIO Top operating junction temperature LM117-55 150 LM217-25 to the internal power limit 150LM3170 to 125Ptot Tstg Storage Temperature -65 to 150 LM317 works: LM317 input maximum voltage of 30 V, output voltage 1.

5 - 32V. 1. 5A. But with the current time to pay attention to power consumption. attention to heat dissipation. LM317 has three pins. An input an output of a voltage regulator. Positive voltage input pin, output pin is connected to the load, the voltage adjust pin of a pin resistor (200 or so) in the output pin, and the other connected variable resistor (a few K) connected to the ground. Input and output pins filter capacitor to be connected to ground. : Isolated refers to the input and output terminal isolation transformer isolation transformer may be the frequency that may be.

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