The L7818 is a DC-DC voltage regulator IC that can handle an input voltage range of up to 35V and output a fixed voltage of 18V at up to 1.5A of current. It is commonly used in various electronic devices and circuits that require a stable and reliable 18V power supply. The IC contains built-in thermal and short-circuits protection, and its compact size and ease of use make it a popular choice for both hobbyist and professional electronics applications.

 

Package Includes:

• 1 x L7818 DC-DC voltage regulator IC

 

Features:

1. Input voltage range up to 35V
2. The fixed output voltage of 18V
3. The maximum output current of 1.5A
4. Built-in thermal shutdown and short-circuit protection
5. Low dropout voltage
6. Internal current limiting and thermal limiting
7. Requires minimal external components for stability
8. Available in various package types, including TO-220
9. Operating temperature range from -40°C to 125°C
10. Wide application range including audio amplifiers, motor controllers, and microcontroller power supplies
11. Easy to use and integrate into circuits.

 

Description:

The L7818 is a linear voltage regulator IC that is designed to regulate an input voltage of up to 35V down to a fixed output voltage of 18V. It is part of the L78 series of positive voltage regulators, which includes various models capable of outputting different fixed voltages. The L7818 can supply up to 1.5A of current, making it suitable for a wide range of applications. It is commonly used in electronic devices and circuits that require a stable and reliable 18V power supply, such as audio amplifiers, motor controllers, and power supplies for microcontrollers. One of the benefits of using the L7818 is it's built-in thermal and short-circuit protection. The IC has a built-in thermal shutdown circuit that prevents the device from overheating and causing damage. It also has a built-in current limiting circuit that protects against short circuits and overloads. The L7818 is easy to use and can be incorporated into circuits with minimal external components. It requires just two capacitors for stability and can operate in a wide range of temperatures, from -40°C to 125°C. The IC is available in various package types, including TO-220 and TO-3, making it compatible with a wide range of circuit board layouts.

 

Principle of Work:

The L7818 voltage regulator IC is a linear voltage regulator that works by regulating the input voltage and maintaining a stable output voltage of 18V. The IC has a built-in voltage reference and error amplifier that compares the input voltage to the output voltage and adjusts the output voltage as necessary to maintain a constant 18V output.

The input voltage is connected to the input pin of the IC, and the output voltage is obtained from the output pin. The voltage regulator has an internal pass transistor that controls the voltage at the output pin. When the input voltage is applied to the voltage regulator, the internal pass transistor conducts and allows the input voltage to pass through to the output pin. The error amplifier compares the output voltage to a reference voltage and adjusts the output voltage by controlling the conduction of the pass transistor. If the output voltage increases above the desired 18V, the pass transistor is turned off, and if the output voltage decreases below 18V, the pass transistor is turned on. This feedback loop keeps the output voltage constant at 18V, even when the input voltage fluctuates.

The L7818 IC also has built-in thermal and short-circuit protection circuits that prevent the device from overheating and causing damage. The thermal protection circuit turns off the internal pass transistor if the IC's temperature exceeds a safe limit, while the short-circuit protection circuit limits the output current to a safe level in case of a short circuit.

 

Pinout of the Module:

• Vin: Input voltage pin. Connect this pin to the input voltage source that you want to regulate to 18V.
• GND: Ground pin. Connect this pin to the ground of your circuit.
• Vout: Output voltage pin. Connect this pin to the load that requires a regulated 18V voltage.

It is important to note that the L7818 voltage regulator IC requires a minimum input voltage of 20V to regulate the output voltage to 18V. The input voltage should not exceed 35V, as this may cause the voltage regulator to overheat and fail. Additionally, a suitable heat sink should be used to dissipate the heat generated by the IC to avoid a thermal shutdown.

 

Applications: 

1. Power supply for audio amplifiers: The L7818 voltage regulator IC can be used to provide a stable 18V DC power supply to audio amplifiers.
2. Power supply for microcontrollers: The L7818 voltage regulator IC can be used to provide a stable 18V DC power supply to microcontrollers and other digital circuits.
3. Power supply for sensors: The L7818 voltage regulator IC can be used to provide a stable 18V DC power supply to sensors and other analog circuits.
4. Battery charging circuits: The L7818 voltage regulator IC can be used in battery charging circuits to regulate the charging voltage to a stable 18V DC.
5. Industrial control systems: The L7818 voltage regulator IC can be used in industrial control systems that require a stable and reliable power supply.

 

Circuit:

• To ensure optimal performance and a long lifespan of the L7818 voltage regulator IC, it is recommended that the load does not exceed 1.5A. Additionally, it is important to use a suitable heatsink with the IC to dissipate any excess heat generated during operation.
• When supplying power to the L7818 voltage regulator IC, it is important to ensure that the input voltage does not exceed 35V. For added safety, it is recommended to keep the input voltage under 25V to 30V.
• It is important to note that the L7818 voltage regulator IC should be operated within a temperature range of -40°C to +125°C. Operating the IC below 0°C or above +125°C can cause damage to the device and reduce its lifespan.
• During storage, it is recommended to keep the L7818 voltage regulator IC within a temperature range of -65°C to +150°C. This ensures that the IC is not exposed to extreme temperatures that could damage the device or cause it to malfunction.

 

Library:

No library needed

                     

Code:  

No code needed

 

Technical Details:

• Output voltage: 18V
• Output current: up to 1.5A
• Input voltage: up to 35V
• Dropout voltage: 2V (typical)
• Quiescent current: 5mA (typical)
• Thermal shutdown protection
• Overcurrent protection
• Short-circuit protection
• Operating temperature range: -40°C to +125°C
• Storage temperature range: -65°C to +150°C
• Package: TO-220 

 

Resources:

• Documentation

 

Comparisons:

The L7818 and LM317 voltage regulator ICs are similar in that they both regulate voltage and provide overcurrent and thermal protection. However, there are some differences between the two:

1. Output voltage: The LM317 is an adjustable voltage regulator, meaning its output voltage can be varied using an external resistor. The L7818, on the other hand, has a fixed output voltage of 18V.
2. Maximum output current: The LM317 can provide up to 1.5A of current, similar to the L7818. However, some models of the LM317 can provide higher current up to 5A or more with the use of an external transistor.
3. Dropout voltage: The LM317 has a lower dropout voltage than the L7818. This means that it can regulate voltage even when the input voltage is very close to the output voltage, making it more efficient.
4. Adjustability: The LM317's adjustability allows it to be used in a wider range of applications. However, the L7818's fixed output voltage can simplify the design and reduce the complexity of the circuit.