7815 Voltage Regulator Pinout, Datasheet, and Uses

Voltage regulators are widely utilized in electrical projects to maintain a stable output voltage irrespective of the incoming voltage. Among the LM78XX series of integrated circuits, the LM7815 rectifier holds significance. The LM7815 is a dedicated integrated circuit voltage regulator with a set output voltage catering to various applications.  The rectifiers in this series are characterized by having three pins and delivering a predetermined output voltage. However, each voltage regulator in the LM78XX series is designed to provide distinct fixed-output voltages. This versatility makes the LM78XX series voltage regulators suitable for various applications. The 7805 voltage regulator delivers a positive voltage of 15V, establishing a convenient power supply for most TTL components. This article will delve into the LM7815 voltage regulator, exploring its features and applications in projects.

What is 7815 Voltage Regulator?

Voltage regulators play a crucial role in electronic circuits by maintaining a consistent output voltage despite fluctuations in input voltage. The designation "7815" carries two key indications: "78" denotes its nature as a positive voltage regulator, while "15" specifies the provided output voltage as 15V. Consequently, our 7805 yields a +15V output voltage.

Although the IC can handle an output current of up to 1.5A, it is susceptible to significant heat dissipation. Therefore, using a heat sink for projects with higher current consumption is advisable. For instance, if the input voltage is 20V, and the load draws 1A, the heat dissipation would be (20-5) * 1 = 15W.

Moreover, the regulator, delivering a positive 15V, can supply ample power to most TTL components. Notably, the regulator is packaged in TO-220, TO-3, TO-220FP, and D2PAK formats.

Using a heat sink becomes crucial to managing thermal issues and preventing excessive heat dissipation from the IC, especially for energy-intensive projects. An example of such a project is the local on-card regulation application. This application effectively addresses distribution challenges associated with single-point regulation. Additionally, terminal regulators are pivotal in constructing logic systems and HiFi setups.

Note: It's important to note that the input voltage for the LM7815 should consistently fall within the range of 17V to 35V. Input voltages below 17V may lead to an unstable output. Furthermore, the voltage regulator needs a minimum of 2V above its fixed output for efficient operation and reliable performance. However, supplying a voltage exceeding 35V is not advisable, as it can damage the device.

LM7815 Pinout

The LM7815 voltage regulator belongs to the category of 3-terminal regulators, featuring input, output, and ground pins, each serving distinct functions. The following table outlines the roles of each pin.

LM7815 Pin Diagram

Pin Configuration

Pin No.	Pin Name	Description
1	Input (V+)	Unregulated Input Voltage
2	Ground	Connected to Ground
3	Output (Vo)	Outputs Regulated +5V

Features & Specifications

• Positive 15V Voltage Regulator

• Minimum Input Voltage: 17V

• Maximum Input Voltage: 35V

• Output Current: 1.5 A

• Includes Internal Thermal Overload and Short Circuit Current Limiting Protection

• Incorporates an In-Built Short Circuit Shut Down Function

• Equipped with an In-Built Heat Shut Down Function

• Utilizes a Backup Current of 8mA

• Maximum Junction Temperature: 125 degrees Celsius

• Available in TO-220, TO-3, and KTE Packages

7815 Application

The 7815 voltage regulator is extensively utilized in various electronic devices and systems. It plays a key role in diverse applications, including:

• Stable +15V output regulator designed for powering microcontrollers and sensors in various projects

• Configurable Output Regulator

• Current Limiting feature for specific applications

• Controlled Dual Supply

• Circuit for Protection Against Output Polarity Reversal

Here are the specific uses:

Power Supply Units: The 7815 regulator is commonly integrated into power supply circuits to provide a steady and regulated +15V output. This voltage level proves suitable for powering a broad spectrum of electronic components, encompassing microcontrollers, sensors, and integrated circuits.

Audio Equipment: Consistency in power supply is paramount in audio amplifiers and related devices to prevent voltage fluctuations that could adversely affect sound quality. The 7815 regulator ensures a constant voltage source, contributing to optimal audio performance.

Automotive Systems: The stable regulation of voltage is essential in automotive electronics to safeguard sensitive components from potential damage due to voltage spikes. The 7815 regulator is frequently applied in various automotive systems, including engine control units (ECUs), dashboard instruments, and lighting controls.

Industrial Control Systems: Numerous industrial applications depend on precise and stable voltage levels for control systems and instrumentation. The 7815 regulator maintains reliable voltage outputs in industrial automation, motor control, and process control systems.

DIY Projects: Enthusiasts and hobbyists often integrate the 7815 regulator into their do-it-yourself (DIY) projects. Whether constructing a power supply for small electronic circuits or designing custom electronic systems, the 7815 regulator provides a convenient and dependable solution for achieving a regulated +15V voltage.

How to Use 7815 Voltage Regulator?

7815 as +15V Voltage Regulator

This represents a standard application circuit for the 7815 IC. Two capacitors with values of 0.33uF and 0.1uF are required to operate this IC. The 0.33uF input capacitor, a ceramic type, addresses input inductance issues, while the 0.1uF output capacitor, also ceramic, contributes to circuit stability. Placing these capacitors close to the terminals enhances their effectiveness. It is essential to use ceramic capacitors, which exhibit faster performance than electrolytic capacitors.

Additional tips

To ensure prolonged and stable operation of your regulator, it is advisable to employ a heat sink when used for extended durations. Additionally, refrain from imposing loads exceeding 1.5A and avoid subjecting it to voltages surpassing 35V. Furthermore, maintain the operational temperature of your device within the range of 0 to 125 degrees Celsius. Also, store your electrical device in environments with temperatures ranging from -65 to 150 degrees Celsius.

7815 Power Supply Circuit Diagram

Continuous adjustable dual power supply (symmetric positive and negative power supply). This circuit is formed by symmetrically connecting an LM7815 and an LM7915 three-terminal voltage regulator, obtaining stable positive and negative power supplies. The output voltage values can be individually adjusted or synchronized.

The attached diagram shows that the circuit rectifies the AC dual 18V voltage output from the transformer through D1 to D4 and filters with C1 and C2 to obtain a DC voltage. The center tap of the transformer's dual power supply serves as the common ground terminal. This DC voltage's positive and negative terminals are then connected to the ① pin of LM7815 and the ③ pin of LM7915, respectively. The ③ pin of LM7815 is connected to the sliding contact "d" of potentiometer W2, and the ① pin of LM7915 is connected to the sliding contact "C" of potentiometer W1. By grounding the sliding contact "C" at the "0" end and adjusting W2, a positive variable voltage of "+6V to +15V" can be obtained from terminal "a." If the sliding contact "d" is grounded at the "0" end and W1 is adjusted, a negative variable voltage of "-6V to -15V" can be obtained from terminal "b". Replacing W1 and W2 with coaxial potentiometers will result in an adjustable symmetrical power supply, with continuously adjustable output voltage values between ±6V to ±15V, achieving synchronized adjustment.

Heat sinks should be added to this circuit's LM7815 and LM7915 three-terminal voltage regulators for cooling purposes.

Advantages of 7815 Voltage Regulator

• The 7815 voltage regulator IC does not necessitate any component for balancing or saturating its output voltage.

• The 7815 IC incorporates built-in protection against high currents. Including a heat sink connected to the common ground is instrumental in preventing the regulator IC from overheating and short circuits, rendering it reliable in various applications.

7815 Equivalents

The 7815 voltage regulator belongs to the 78xx series of linear voltage regulators. If you seek an alternative to the 7815 regulator, numerous options from different manufacturers provide comparable functionality and specifications. Here are some commonly utilized equivalents:

• LM7815: The LM7815, part of the LM78xx series by Texas Instruments, is a well-known equivalent to the 7815 regulator. It shares the same pin configuration and operates with identical input and output voltage specifications.

• UA7815: Manufactured by Fairchild Semiconductor, the UA7815 is another equivalent voltage regulator that delivers functionality and performance similar to the 7815. It is part of the UA78xx series of fixed voltage regulators, offering a regulated +15V output.

• L7815: STMicroelectronics produces the L7815 voltage regulator, an equivalent alternative to the 7815 regulator. As a member of the L78xx series, it provides a regulated +15V output.

• KA7815: The KA7815, produced by various semiconductor companies, is a compatible alternative. It belongs to the KA78xx series and is a fixed +15V voltage regulator.

When choosing an equivalent voltage regulator, reviewing the datasheet and specifications is crucial to ensure compatibility with your specific application requirements. Consider factors such as input voltage range, output current capability, thermal considerations, and any features or characteristics relevant to your project.

7805 vs 78L05

• Introduction

The LM7805 is a voltage regulator designed to deliver a +5-volt output with a current capacity of 1 A. Like many other regulators available, it follows the standard three-pin IC configuration: an input pin for receiving incoming DC voltage, a ground pin to establish the ground reference, and an output pin responsible for providing the positive 5 volts.

The LM78L05 belongs to the LM78Lxx series, a family of positive voltage regulators. This particular IC delivers a fixed output of 5 V with a DC capacity of 100 mA.

• Part Numbers

Its original manufacturer part number is identified as 7805. In this numbering scheme, "78" indicates positive voltage, with "79" indicating negative voltage, and "05" specifically denoting a positive 5 V output.

The letters between "78" and "05" signify the current rating. For instance, "78L05" corresponds to low current (0.1 A), "78M05" denotes medium current (0.5 A), "78S05" indicates high current (2 A), and "78T05" represents an even higher current, possibly reaching 3 A. In contrast, "7805" typically has a current rating of 1 A.

The last two digits in the part number designate various output voltages. For instance, 7805 delivers a 5 V output, 7806 produces a 6 V output, 7808 yields an 8 V output, and so forth.

• Substitution

In many instances, the 78L05 can substitute for the 7805, although they exhibit differences. While their functionalities align, their pin configurations differ; for the 7805, pins 1, 2, and 3 denote input, ground, and output, respectively, whereas for the 78L05, pins 1, 2, and 3 represent output, ground, and input. They are often packaged differently, with the 7805 commonly in a TO-220 package and the 78L05 typically in a TO-92 package. Despite sharing the same output voltage, their output currents vary, with the 78L05 at 0.1 A and the 7805 at 1 A. Physically, the 78L05 is smaller than the 7805, allowing for less power dissipation and potentially lower current ratings.

Is the 7815 Voltage Regulator a Transistor?

The 7815 voltage regulator distinguishes itself from a transistor; it operates as an integrated circuit (IC) encompassing a pass transistor within its internal circuitry. This pass transistor plays a crucial role in fine-tuning the output voltage to uphold a consistent regulated voltage level.

If you seek insights into transistors employed in voltage regulator circuits, various transistor types can be utilized based on specific designs and requirements. Bipolar junction transistors (BJTs) and field-effect transistors (FETs) are commonly employed in voltage regulator circuits.

For BJTs, both NPN (negative-positive-negative) and PNP (positive-negative-positive) types find application. Some frequently used BJT types in voltage regulator circuits encompass 2N3055, TIP31, and TIP32, particularly for higher current applications.

In the realm of FETs, both N-channel and P-channel types are viable. Notable choices for N-channel FETs include IRF540, IRFZ44, and IRF3205, while P-channel FETs like IRF9530 and IRF4905 are prevalent in specific applications.

Acknowledging that selecting a specific transistor for a voltage regulator circuit hinges on factors like the desired output voltage, output current requirements, input voltage range, power dissipation, and other application-specific considerations is crucial. Typically, the transistor functions as a power switch or is integrated into the voltage-regulating circuitry, working with other components like resistors, capacitors, and diodes to establish a comprehensive voltage regulator system.

7815 Package

7815 Datasheet

Download 7815 Datasheet PDF.

Conclusion

The 7815 voltage regulator is versatile and extensively employed, delivering a steadfast and regulated +15V output voltage. Its versatility, applications, and vital specifications position it as crucial in diverse electronic systems, spanning power supplies to automotive and industrial control systems. A comprehensive grasp of its operational principles, attention to key specifications, and adherence to best practices empower you to integrate the 7815 voltage regulator into your projects, ensuring adept and dependable power management.

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