LM7905 Pinout, Equivalent, Application, Datasheet

This article provides a complete technical explanation of the LM7905 pinout, features, specifications, working principle, and practical applications. You will learn how this 3-terminal negative voltage regulator functions, where it is used, and what alternatives exist. This overview ensures you understand the LM7905 thoroughly before moving toward design and implementation.

Introduction

The LM7905 is a fixed −5V negative voltage regulator IC belonging to the popular 79xx family of negative regulators. It provides a stable and regulated −5V output for analog, digital, and embedded systems that require a negative supply rail.
Known for its reliability and simplicity, the LM7905 includes built-in protection features such as thermal shutdown, safe-area protection, and short-circuit protection.
Its 3-terminal design (Input, Ground, Output) makes it extremely easy to use in both hobby and professional circuits, especially for powering operational amplifiers, analog stages, and dual-supply systems.

Pin Configuration / Pinout of LM7905 Power Amplifier IC

Understanding the LM7905 Pinout Configuration

The LM7905 pinout consists of three functional pins:

1. Ground (GND): Common reference point for input and output.
2. Input (Vin): Receives an unregulated negative voltage.
3. Output (Vout): Provides a regulated −5V output.

This simple pinout allows easy PCB integration, making it ideal for low-noise power supplies, analog circuits, and dual-rail amplifier designs.

Note: DATASHEET DOWNLOAD button is provided end of this article.

LM7905 Key Features

• Fixed −5V regulated output
• 3-terminal easy-to-use design
• Internal thermal shutdown protection
• Short-circuit and safe-area protection
• Low output noise and ripple
• Suitable for dual-power supply designs
• Compatible with various load conditions
• Stable with external capacitors

LM7905 Specifications/Characteristics

• Output voltage: −5V fixed
• Input voltage recommended: Up to −35V
• Output current: Typically up to 1A
• Dropout voltage: Standard 79xx-family range
• Protections: Thermal shutdown, current limiting, safe-area
• Total power dissipation (Ptot): Package dependent
• Operating temperature range: 0°C to +125°C
• Storage temperature (Tstg): −65°C to +150°C
• Package types: TO-220, TO-263, TO-252

Key Applications of LM7905 Power Amplifier IC

• Dual power supplies for op-amps (±5V)
• Negative rails for audio amplifier stages
• Analog and mixed-signal circuits
• Instrumentation power supplies
• Bench power supply designs
• Microcontroller and logic circuits requiring −5V
• Communication devices
• Battery-powered equipment needing regulated negative voltage

LM7905 Equivalent ICs / Alternatives

(Verify pin compatibility before using substitutions)

• MC7905
• KA7905
• L7905
• uA7905
• Other 79xx series ICs (for different voltages)
  These alternatives perform similarly and can often be used interchangeably.

More Circuit Layouts

Working Principle of LM7905

The LM7905 works by regulating an unregulated negative input voltage into a stable −5V output using an internal reference and pass-transistor control loop.
When voltage is applied to the input, the internal circuitry maintains the output at −5V regardless of changes in input voltage or load current.
Its built-in protection mechanisms prevent overheating and damage from short circuits, making it ideal for robust power supply designs. Proper input and output capacitors help reduce noise and improve transient response.

Frequently Asked Questions (FAQ)

Q1: What is the output voltage of LM7905?
It provides a fixed and regulated −5V output.

Q2: Can LM7905 be used with LM7805 for dual ±5V supplies?
Yes, it is commonly paired with LM7805 to generate ±5V rails.

Q3: What capacitors are needed?
A small input capacitor (0.33µF) and an output capacitor (0.1µF to 1µF) are recommended for stability.

Q4: What is the maximum current output?
Typically up to 1A depending on package and heat dissipation.

Q5: Does LM7905 require a heatsink?
A heatsink is recommended when driving higher loads or when the input voltage is significantly higher than −5V.

Conclusion

The LM7905 is a reliable and simple negative voltage regulator IC ideal for generating a stable −5V supply in analog, digital, and embedded circuits. Its 3-terminal design, built-in protections, and easy implementation make it one of the most commonly used regulators for dual-supply and low-noise circuits. Whether for audio, instrumentation, or general power design, the LM7905 remains a trusted choice.

Datasheet of LM7905 Power Amplifier IC

Click the following Button below to download the datasheet of LM7905 :

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