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LM317K
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LM317K

Product Overview

Category: Integrated Circuit (IC)

Use: Voltage Regulator

Characteristics: - Adjustable output voltage - High current capability - Thermal overload protection - Short circuit protection

Package: TO-3 metal can package

Essence: The LM317K is a three-terminal positive voltage regulator IC that provides a regulated output voltage adjustable between 1.2V and 37V.

Packaging/Quantity: The LM317K is typically sold in packs of 10 or more.

Specifications

  • Input Voltage Range: 4.2V to 40V
  • Output Voltage Range: 1.2V to 37V
  • Output Current: Up to 1.5A
  • Line Regulation: 0.01%/V
  • Load Regulation: 0.1%
  • Dropout Voltage: 1.5V
  • Temperature Range: -40°C to +125°C

Pin Configuration

The LM317K has three pins:

  1. Adjust: This pin is used to set the desired output voltage by connecting an external resistor network.
  2. Output: The regulated output voltage is obtained from this pin.
  3. Input: The input voltage is applied to this pin.

Functional Features

  • Adjustable Output Voltage: The LM317K allows the user to adjust the output voltage according to their specific requirements.
  • High Current Capability: With a maximum output current of 1.5A, the LM317K can handle a wide range of applications.
  • Thermal Overload Protection: The IC incorporates thermal overload protection, preventing damage due to excessive heat.
  • Short Circuit Protection: The LM317K includes short circuit protection, safeguarding the device and connected components.

Advantages and Disadvantages

Advantages: - Wide input voltage range - Adjustable output voltage - High current capability - Thermal and short circuit protection

Disadvantages: - Dropout voltage of 1.5V may limit some low voltage applications - Requires external resistor network for voltage adjustment

Working Principles

The LM317K is a linear voltage regulator that uses an adjustable precision reference to maintain a constant output voltage. The adjust pin is connected to an external resistor network, which sets the desired output voltage. The IC compares the reference voltage with the feedback voltage from the resistor network and adjusts the pass transistor accordingly to regulate the output voltage.

Detailed Application Field Plans

The LM317K finds applications in various fields, including:

  1. Power Supply Design: The LM317K is commonly used in power supply circuits to provide a regulated voltage for electronic devices.
  2. Battery Charging: It can be used in battery charging circuits to regulate the charging voltage and prevent overcharging.
  3. Audio Amplifiers: The LM317K can be employed in audio amplifier circuits to provide a stable power source for amplification stages.
  4. LED Lighting: It is suitable for driving LEDs by regulating the voltage and current to ensure optimal performance and longevity.

Detailed and Complete Alternative Models

Some alternative models to the LM317K include:

  1. LM317T: Similar to the LM317K, but in a TO-220 package.
  2. LM350: Higher current capability (up to 3A) and lower dropout voltage compared to LM317K.
  3. LM338: Adjustable output voltage up to 32V and higher current capability (up to 5A).

These alternative models offer similar functionality but may have different package options, current capabilities, or voltage ranges.

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Seznam 10 běžných otázek a odpovědí souvisejících s aplikací LM317K v technických řešeních

Sure! Here are 10 common questions and answers related to the application of LM317K in technical solutions:

  1. Q: What is LM317K? A: LM317K is a popular adjustable voltage regulator integrated circuit (IC) that can provide a regulated output voltage ranging from 1.2V to 37V.

  2. Q: How does LM317K work? A: LM317K works by adjusting its output voltage based on the resistance between its ADJ pin and the OUT pin, allowing for precise voltage regulation.

  3. Q: What is the maximum current that LM317K can handle? A: LM317K can handle a maximum current of 1.5A when properly heatsinked.

  4. Q: Can LM317K be used as a constant current source? A: Yes, LM317K can be configured as a constant current source by using an external resistor connected between the ADJ pin and the OUT pin.

  5. Q: How do I calculate the value of the external resistor for LM317K to achieve a desired output voltage? A: The formula to calculate the value of the external resistor is R = (Vout / 1.25) - 1, where Vout is the desired output voltage.

  6. Q: Can LM317K handle input voltages higher than the desired output voltage? A: Yes, LM317K can handle input voltages higher than the desired output voltage, but a proper heatsink may be required to dissipate excess heat.

  7. Q: Is it possible to use LM317K in parallel to increase the output current? A: Yes, LM317K can be used in parallel to increase the output current, but each LM317K should have its own current-limiting resistor to ensure equal current sharing.

  8. Q: Can LM317K be used in battery charging applications? A: Yes, LM317K can be used in battery charging applications by adjusting the output voltage to match the desired charging voltage for the battery.

  9. Q: What are the typical applications of LM317K? A: LM317K is commonly used in power supplies, battery chargers, adjustable voltage regulators, and other applications requiring precise voltage regulation.

  10. Q: Are there any precautions to consider when using LM317K? A: Yes, some precautions include proper heatsinking if operating at high currents or with high input-output voltage differentials, avoiding short circuits, and ensuring correct pin connections as per the datasheet.