LM258 – Dual Operational Amplifier IC

28 October 2018 - 0 Comments

LM258 Dual Op-amp

LM258 Dual Op-amp Pinout

LM258 is dual operational amplifiers IC and is a member of ‘LMxx’ family. The ‘LM’ series originated with integrated circuits made by National Semiconductor. The prefix ‘LM’ stands for linear monolithic, referring to the analog components integrated onto a single piece of silicon. The chip consists of two independent, high gain, internally frequency compensated operational amplifiers which were designed specifically to operate from a single power supply over a wide range of voltages. Operation from split power supplies is also possible and the low power supply current drain is independent of the magnitude of the power supply voltage.

Pin configuration

LM258 is an eight pin device as shown in above pin diagram and description for each pin is given below.

Pin	Name	Description
1	1OUT	Output pin of the Op-amp 1
2	1IN-	Inverting input of Op-amp 1
3	1IN+	Non-Inverting input of Op-amp 1
4	GND	Ground
5	2IN+	Non-Inverting input of Op-amp 2
6	2IN-	Inverting input of Op-amp 2
7	2OUT	Output pin of the Op-amp 2
8	VCC	Power supply

The device is available in many packages the user can choose depending on requirement.

Features and Electrical characteristics of LM258

Wide range of supply voltage
Can work from single power supply
Two individually operated operational amplifiers
Low noise interference among op-amps
Wide Bandwidth (Unity Gain): 1 MHz
Large DC Voltage Gain: 100 dB
Low Input Offset Voltage: 2 mV
Input common-mode voltage range includes ground
Differential input voltage range equal to the power supply voltage
Internal Frequency Compensation
Single Supply Operation: +3.0 V to +32 V
Dual Supply Operation: +16V and -16V
Very Low Supply Current Drain (500µA)
Operating temperature: -25ºC to 85ºC
Total power dissipation: 830mW

Similar ICs

LM158, LM158A, LM358, LM358A, LM2904, LM2904Q, LM4558, LM747

Overview of LM258 Op-amp

LM258 IC can be used to realize general purpose op-amp operation circuits like comparator, differential amplification or mathematical operations. Moreover the device specifically designed for applications like transducer amplifiers, dc amplification blocks to be implemented more easily in single-supply-voltage systems. For example, these devices can be operated directly from the standard 5V supply used in digital electronics without additional -5V supply.

In addition with two of those op-amp on board the device can perform two different functions at a time which comes in handy in applications. The device is popular among hobbyists and engineers for being low cost and good performance.

How to use LM258 IC

As mentioned earlier there are two op-amps in the LM258 IC and they are connected internally as shown below.

LM258 Internal Structure

Here theses two op-amps can be used to realize any of op-amp application circuits like amplifier, comparator, oscillators and mathematical operations. So we will construct a simple Non inverting amplifier to understand the use of device.

Now let us take a single op-amp from the two and construct a simple application circuit as show below.

LM258 Application Circuit

In the above circuit the op-amp acts as a Non-Inverting Amplifier (Since input is given to Non-inverting terminal of op-amp) and output is provided as Vo. Also the device is powered from single voltage source of VCC.

We have the equation for the output Vo =Input voltage * Gain = Vi * A = Vi * (1+R1/R2)

For example:

Say R1 = 100, R2 = 10 and Input voltage Vi = 20mV

We will have Vo = 20m*(1+10)=220mV

With that we have realized the amplifier circuit of op-amp and in a similar way we use the device to design all other application circuits of op-amp.