LM7905 Voltage Regulator Pinout, Specs, Circuit, and Datasheet

A voltage regulator is an essential electronic component that maintains a constant output voltage regardless of variations in input voltage or load conditions. It ensures that electronic devices receive a stable and reliable power supply, which is crucial for their optimal performance and longevity.

Voltage regulators play a critical role in electronic circuits by protecting sensitive components from voltage fluctuations. They help prevent damage, improve efficiency, and ensure the consistent operation of various devices, from simple gadgets to complex industrial systems. This article will explore one of the most commonly used regulator ICs: the LM7905 Voltage Regulator IC. It will cover its pinout, circuit, specifications, datasheet, and more details.

What is LM7905?

The 7905 IC is a negative 5V regulator, meaning it provides -5V as its output. The name "7905" signifies two things: "79" indicates that it is a negative voltage regulator, and "05" means it provides a 5V output. Thus, the 7905 outputs a -5V voltage.

This IC can supply up to 1.5A of current. However, it experiences significant heat loss, so a heat sink is recommended for projects that consume higher currents. For instance, if the input voltage is 12V and you're drawing 1A, then (12-5) * 1 = 7W. This 7 watts will be dissipated as heat.

LM7905 Pinout

LM7905 Pin Configuration

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

Features & Specifications

• Negative Voltage Regulator

• Output Voltage: -5V

• Output Current: 1.5A

• Minimum Input Voltage: 7V

• Maximum Input Voltage: 25V

• Output Current in Excess of 1A

• Operating Current (IQ): 5mA

• Short Circuit Protection

• Output Transistor Safe Operating Area Compensation

• Internal Thermal Overload and Short Circuit Current Limiting Protection

• Maximum Junction Temperature: 125°C

• Available in TO-220 and KTE packages

The Function Negative Voltage Regulators

Negative voltage regulators are primarily utilized in operational amplifier (Op-Amp) and other circuits requiring a negative supply voltage. Often, in scenarios where an Op-Amp operates in a dual-mode power supply, these 79XX ICs regulate the negative voltage. Additionally, these ICs can source current into the ground rail rather than sinking it, which is typically the case.

7905 IC As -5V Voltage Regulator

Here is a typical application circuit for the 7905 IC. To make this IC work, you only need two capacitors: one with a value of 2.2µF and another with a value of 1µF.

The 2.2µF input capacitor is a ceramic capacitor that addresses input inductance issues, while the 1µF output capacitor, also ceramic, enhances the circuit's stability. These capacitors should be placed close to the terminals for optimal effectiveness. Ceramic capacitors are recommended because they are faster than electrolytic capacitors.

LM7905 Application

• Constant -5V output regulator for op-amp signals

• Adjustable Output Regulator

• Current Limiter for certain applications

• Regulated Dual Supply

• Dual Power Supplies

• Voltage converter circuits

• Voltage step-down circuits

• Battery Chargers

• Motor Drivers applications

LM7905 Equivalents/Alternatives

When considering alternatives to the LM7905 regulator IC, several options provide different voltage outputs and functionalities, making them suitable for various applications:

LM7806: The LM7806 is a fixed-voltage regulator that provides a stable 6V output. It is an ideal alternative to the LM7905 when a slightly higher voltage is required in your circuit design.

LM7809: The LM7809 offers a fixed 9V output, making it suitable for applications that need a moderate voltage increase compared to the LM7905. This regulator is often used in audio and telecommunications equipment.

LM7812: The LM7812 provides a 12V output and is commonly used in higher voltage applications such as motor controllers and power supplies. It can be an excellent choice when a higher voltage level is necessary compared to the 5V provided by the LM7905.

LM317: The LM317 is an adjustable voltage regulator that allows the user to set the output voltage to any desired level within a specified range. This flexibility makes it a versatile alternative to the fixed-voltage LM7905 for various custom voltage requirements.

LM7805: The LM7805 is a fixed 5V regulator, similar to the LM7905 but providing a positive voltage output. It is widely used in digital circuits, microcontroller-based projects, and other applications that require a stable 5V supply.

LM7912: The LM7912 is a negative voltage regulator like the LM7905 but provides a -12V output. It is suitable for applications that need a higher negative voltage and is commonly used in dual power supply configurations.

LM117V33: The LM117V33 is an adjustable voltage regulator that can provide an output voltage of 3.3V. This regulator is ideal for low-voltage applications and offers more precise control over the output voltage compared to the fixed LM7905.

XC6206P332MR: The XC6206P332MR is a low dropout regulator (LDO) that provides a 3.3V output. It is suitable for battery-powered and low-voltage applications where energy efficiency is critical. This regulator offers an alternative for designers looking for a low-voltage solution compared to the -5V output of the LM7905.

LM7905 Package

LM7905 Datasheet

Download LM7905 Datasheet PDF.

LM7805 vs. LM7905

Feature	LM7805	LM7905
Type	Fixed Positive Voltage Regulator	Fixed Negative Voltage Regulator
Output Voltage	+5V	-5V
Output Current	Up to 1A	Up to 1A
Input Voltage Range	7V to 35V	-7V to -25V
Temperature Range	-40°C to +125°C	-40°C to +125°C
Line Regulation	0.01% (typical)	0.2% (typical)
Load Regulation	0.1% (typical)	1% (typical)
Dropout Voltage	2V (typical)	2V (typical)
Package Options	TO-220, TO-263, DPAK	TO-220, TO-263
Application	Power supply circuits, +5V supplies	Negative voltage applications, biasing circuits
Thermal Shutdown	Yes	Yes
Current Limit	Yes	Yes

• LM7805: A fixed positive voltage regulator providing a stable +5V output, ideal for various applications requiring a consistent positive voltage supply.

• LM7905: A fixed negative voltage regulator designed to deliver a stable -5V output, suitable for applications that require negative voltage supply.

LM317 vs. LM7905

Feature	LM317	LM7905
Type	Adjustable Voltage Regulator	Fixed Negative Voltage Regulator
Output Voltage Range	1.25V to 37V	-5V
Output Current	Up to 1.5A	Up to 1A
Input Voltage Range	3V to 40V	-7V to -25V
Temperature Range	-40°C to +125°C	-40°C to +125°C
Line Regulation	0.01% (typical)	0.2% (typical)
Load Regulation	0.1% (typical)	1% (typical)
Dropout Voltage	3V (typical)	2V (typical)
Package Options	TO-220, TO-263, DPAK	TO-220, TO-263
Application	Power supply circuits, adjustable power supplies	Negative voltage applications, biasing circuits
Thermal Shutdown	Yes	Yes
Current Limit	Yes	Yes

• LM317: An adjustable voltage regulator suitable for various applications requiring a specific output voltage, capable of supplying up to 1.5A with a wide input voltage range.

• LM7905: A fixed negative voltage regulator designed for applications that require a stable -5V output, suitable for supplying up to 1A in negative voltage configurations.

Conclusion

The LM7905 voltage regulator is a versatile and reliable component for providing a stable -5V output. It is widely used in various applications, from analog circuits to automotive electronics, due to its simplicity and performance.

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