LM358 Op Amp Pinout, Circuit and Equivalent

LM358 IC (Dual comparator) Basic Electronics

In this article, we will explore the LM358 pinout, working principle, circuit applications, and equivalent alternatives. Whether you are an electronics hobbyist or an engineer, understanding how to use LM358 effectively will help you in designing efficient analog circuits.

What is LM358?

The LM358 is a widely used dual operational amplifier IC known for its low power consumption, wide voltage range, and versatility, integrating two independent, high-gain, frequency-compensated op-amps into a single package, making it ideal for sensor signal amplification, voltage monitoring, active filters, and various analog circuits, especially in low-power and battery-operated applications.

Key Features of LM358

• Dual op-amp configuration in a single package.
• Wide supply voltage range: 3V to 32V (single supply) or ±1.5V to ±16V (dual supply).
• Low power consumption (0.7mA typical quiescent current).
• Internally frequency-compensated for stable performance.
• High input impedance and low output impedance.
• Common-mode input voltage range includes ground, making it ideal for single-supply applications.

LM358 Pinout and Internal Structure

The LM358 op amp is an 8-pin integrated circuit (IC) that contains two independent operational amplifiers. It is available in different package types, including DIP-8, SOIC-8, and TSSOP-8, making it suitable for both through-hole and surface-mount applications.

Pin Number	Name	Description
1	Out1	Output of Op-Amp 1
2	In1-	Inverting Input of Op-Amp 1
3	In1+	Non-Inverting Input of Op-Amp 1
4	Vcc-	Negative Power Supply (Ground)
5	In2+	Non-Inverting Input of Op-Amp 2
6	In2-	Inverting Input of Op-Amp 2
7	Out2	Output of Op-Amp 2
8	Vcc+	Positive Power Supply

How Does LM358 Work? (Working Principle)

The LM358 operational amplifier follows the fundamental principles of op-amp operation:

Differential Amplification:

The op-amp amplifies the voltage difference between its inverting (-) and non-inverting (+) inputs.

1. If IN+ voltage > IN- voltage, the output swings high.

2. If IN- voltage > IN+ voltage, the output swings low.

Voltage Gain:

The open-loop gain of LM358 is very high (~100,000).

In practical circuits, feedback resistors are used to control the gain.

Single-Supply Operation:

Unlike some op-amps requiring dual supplies, LM358 can operate with a single power source, making it ideal for battery-powered circuits.

LM358 Circuit Design

When designing with the LM358 op amp, consider power supply, feedback resistance, output limits, and stability for optimal performance in amplification, filtering, and comparator circuits.

Power Supply Selection:

1. LM358 works well with single-supply (5V-32V) or dual-supply (±1.5V to ±16V).
2. Ensure the power supply voltage matches the intended application.

Choosing the Right Feedback Resistors:

For amplification circuits, select resistor values to control the gain effectively.
High-value resistors increase gain but can introduce noise.

Avoiding Output Swing Limitations:

LM358 does not output rail-to-rail voltage. The output is typically 1.5V lower than V+ in single-supply mode.

Input Voltage Considerations:

LM358’s common-mode voltage range includes ground, making it ideal for single-supply applications.

Use Proper Decoupling Capacitors:

Place 0.1µF and 10µF capacitors near the LM358 power pins to stabilize the circuit and reduce noise.

LM358 Applications

The LM358 operational amplifier is popular in analog circuits because of its low power consumption, single-supply operation, and versatility. It is commonly used for signal amplification, voltage comparators and motor control.

Signal Amplification – Boosts weak sensor signals (e.g., temperature and light sensors) for better processing.

Voltage Comparator – Compares input voltages for battery level indicators and automatic switches.

Active Filters – Used in audio processing and signal conditioning to remove noise.

LED and Battery Indicators – Monitors power levels and controls LED status indicators.

Motor Control – Regulates motor speed and direction using PWM techniques.

The LM358’s versatility makes it essential for DIY electronics and industrial applications.

LM358 with Arduino and Projects

The LM358 is commonly used in Arduino projects for signal amplification, voltage comparison, and sensor interfacing. It operates on a single power supply and is ideal for low-power applications.

Interfacing LM358 with Arduino

• Power: Can be powered by Arduino’s 5V or an external source.
• Inputs: Connect sensors to the inverting (-) and non-inverting (+) terminals.
• Output: Send the processed signal to an Arduino analog input.

Common LM358 Projects

1. Sensor Signal Amplification – Boosts weak signals (e.g., microphone, photoresistor).
2. Voltage Comparator – Detects threshold changes (e.g., battery monitoring).
3. Audio Preamp – Enhances audio signals for processing.
4. Light Following Robot – Processes LDR signals for motor control.
5. Temperature-Based Fan Control – Regulates PWM fan speed via LM35 sensor.

With LM358, Arduino projects gain better analog signal handling for automation and control.

LM358 Equivalent and Alternatives

There are several equivalent and alternative op-amps that can replace the LM358 based on specific requirements:

Picture	Model	Manufacturer	Supply Voltage (V)	Gain Bandwidth (MHz)	Slew Rate (V/µs)	Input Offset Voltage (mV)	Package Types
	LM358	Texas Instruments	3 – 32	0.7	0.3	2 – 7	SOIC-8, DIP-8, TSSOP-8
	LM2904	Texas Instruments	3 – 32	1.2	0.6	2 – 7	SOIC-8, DIP-8, TSSOP-8
	LM324	Texas Instruments	3 – 32	1.2	0.5	2 – 7	SOIC-14, DIP-14, TSSOP-14
	NE5532	Texas Instruments	3 – 44	10	9	0.3 – 2	SOIC-8, DIP-8, TSSOP-8
	OP07	Analog Devices	3 – 18	0.6	0.3	0.15 – 1	SOIC-8, DIP-8

When to Choose an Alternative?

If you need more than one operational amplifier can choose LM324, the pursuit of high precision can choose OP07, focus on audio performance can choose NE5532.

Common LM358 Package Types

The LM358 is a widely used dual operational amplifier available in various package types to suit different applications. Here are some common LM358 package types and their characteristics:

S08 Package (SOIC-8):

This is a Small Outline Integrated Circuit (SOIC) package with 8 pins, offering good thermal performance and ease of soldering. It is widely used in general-purpose PCB designs.

MiniSO8 Package:

Compared to the standard SOIC-8, the MiniSO8 package is more compact, making it suitable for space-constrained applications such as portable devices and compact circuit designs.

DFN8 2×2 Package:

The Dual Flat No-lead (DFN) package, measuring just 2×2 mm, features a leadless design for improved thermal dissipation and a lower package height, making it ideal for high-density circuit designs.

TSSOP8 Package:

The Thin Shrink Small Outline Package (TSSOP) also features 8 pins but has a thinner and narrower profile, reducing PCB footprint while enhancing thermal performance in high-density electronic applications.

Each package type has its advantages, allowing designers to choose the most suitable option based on their circuit requirements.

Conclusion

The LM358 op amp is an excellent choice for low-power, single-supply applications, including signal amplification, filtering, and comparators. Its dual op-amp configuration, wide voltage range, and low power consumption make it ideal for DIY electronics, Arduino projects, and professional circuit designs.