A quad-operational amplifier is a single-package IC with four independent amplifiers. These operational amplifiers provide good value in terms of cost for each channel and save space on a PCB throughout the layout. So, it is common to utilize in applications such as multiple LED strings, and three-phase motors that sense various currents. So these are frequently used within applications where multiple currents must be detected like in multiple LED strings & three-phase motors. Thus, these ICs are cost-effective and examples are; LM324, LM837, OPA4243, etc. This article elaborates on LM348 IC, pin-out, features, specifications, and applications.
What is LM348 IC?
LM348 IC is a general-purpose, independent & quadruple operational amplifier with high gain. LM348 IC includes four internal amplifiers where isolation can be achieved in between these amplifiers through biasing every amplifier separately. So, this amplifier is internally compensated with similar characteristics to the uA741 IC. So, it can be utilized at different places wherever amplifier matching is required. In addition, its input voltage & input offset current are also below the 741 IC.
These amplifiers are biased with a separate power supply which can be isolated with layout technique. So this amplifier has different features like; low input offset current, input & output overload protection low input offset voltage, and many more.
How LM348 IC Works?
The LM348 integrated circuit works by amplifying the variation within voltage among the two inputs. So this IC is a high-gain, quadruple, and internally compensated operational amplifier with less supply-current drain, input bias & offset currents. This op-amp can also have overload protection mainly for inputs & outputs.
The LM348 IC has similar operating characteristics to the µA741 IC and also has a class-AB output stage including no crossover distortion. Thus, this IC is used interchangeably through the industry-standard LM248 & LM148. The amplifiers in this IC are biased with a separate power supply which can be isolated with the layout method by providing high gain.
LM348 IC Pin Configuration:
The LM348 IC pin configuration is shown below. This IC includes 14 pins which are discussed below.
LM348 IC Pin Configuration
- Pin-1 (OUT-1): It is an output pin of the first amplifier.
- Pin-2 (INV-1): It is an inverting input pin of the first amplifier.
- Pin-3 (NON-INV-1): It is a noninverting input pin of the first amplifier.
- Pin-4 (V+): It is a positive power supply pin of an amplifier IC.
- Pin-5 (NON-INV-2): It is a non-inverting pin of the second amplifier.
- Pin-6 (INV-2): It is an inverting input pin of the second amplifier.
- Pin-7 (OUT-2): It is an output pin of a second amplifier.
- Pin-8 (OUT-3): It is an output pin of a third amplifier.
- Pin-9 (INV-3): It is an inverting input pin of a third amplifier within the IC.
- Pin-10 (NON-INV-3): It is a noninverting input pin of a third amplifier.
- Pin-11 (V-): It is a negative power supply pin of IC.
- Pin-12 (NON-INV4): It is a noninverting input pin of the fourth amplifier.
- Pin-13 (INV-4): It is an inverting input pin of the fourth amplifier.
- Pin-14 (OUT-4): It is an output pin of the fourth amplifier.
Features & Specifications:
The features & specifications of LM348 IC include the following.
- LM348 is an 8-pin operational amplifier with four in-built op-amps within a single package.
- This IC is available in multiple packages like PDIP (N), SOP (NS) & SOIC (D).
- This IC is compatible with the LM124 pin configuration.
- Its operating characteristics are similar to µA741 IC.
- Its typical low supply current drain per amplifier is 0.6 mA.
- It has low input offset voltage and input offset current.
- It has I/O overload protection.
- This IC is designed to interchange with LM248, LM348 & LM148 ICs.
- Its supply current drain is low, like 0.6 m per amplifier.
- This IC’s input offset current is low like 4 nA.
- Its low input offset voltage is 1 mV.
- The low input bias current is 30 nA.
- Its operating temperature ranges from 0°C to 70°Centigrade.
Equivalent & Alternatives
Equivalent to LM348 ICs are OP11, UPC4741C, LM248, LM148, etc. So, alternative LM348 ICs are; LM158, LM358, LM258, LM2904, LM392, LM432, etc.
Microphone Preamplifier Circuit with LM348 IC
The three-input microphone preamplifier circuit with LM348 IC is shown below which provides low noise characteristics, flexible functionalities, and a wide voltage supply that makes it a perfect choice for most audio professionals. So, the LM348 IC is a quad op-amp with four independent amplifiers where every amplifier drives 26mAmps of load current. So its voltage supply ranges from ±3V to ±15V which makes it appropriate for both dual and single supply applications.
LM348 IC ensures precise amplification with just 2mV typical input offset voltage. In addition, it provides up to 0.5V/μs high slew rate which makes it perfect for high-speed audio signal processing.
Thus, the required components to make this circuit mainly include; LM348 IC, 100k potentiometers, resistors like 100k, 1M, and 1k, and capacitors like 1uF & 22uF. Connect this circuit as per the following diagram given.
Microphone Preamplifier Circuit with LM348 IC
Working
The microphone preamplifier circuit utilizes the LM348 IC where this IC plays a key role in amplifying the audio signals from different three microphones concurrently. So, this IC includes four op-amps where three of them are utilized to get input supply from the microphone channels. The fourth amplifier gets the output from those amplifiers. Thus, the fourth amplifier functions as a mixer to mix all signals.
So every microphone in this circuit is connected to a separate input pin of the IC. This op-amp amplifies the signals and drives the output through adequate gain to feed into subsequent audio processing stages like amplifiers or mixers.
This circuit has gained control of every input channel. So each op-amp’s gain of each Op-Amp can be adjusted individually using external resistors by providing flexibility in tailoring the amplification ranges for different microphones. So, the low noise performance of this IC ensures minimum interference and precise sound signal reproduction.
The LM348 IC in this circuit provides an outstanding platform for making a preamplifier circuit with three input microphones. So this circuit provides a variety of options to hold different requirements like adjustable gain compatibility. Audio enthusiasts can design high-quality microphone preamplifiers to deliver precise, noise-free, and crisp sound reproduction by using the LM348 IC. Thus, this IC’s low noise characteristics, versatile functionalities & wide voltage supply range will make it a perfect choice mainly for audio enthusiasts & professionals.
Thus, this microphone preamplifier circuit can be used in video conferencing and courtrooms. Panel discussion and in hotel sound systems.
Advantages & Disadvantages
The advantages of LM348 IC include the following.
- LM348 IC has a wide bandwidth.
- This IC has a low input offset voltage and low quiescent current.
- It has a high open-loop voltage gain.
- It operates above a wide temperature range.
- This IC is pin-compatible through the LM124 IC.
- It has overload protection mainly for inputs & outputs.
- Its operating characteristics are related to the µA741.
- It is a quad op-amp IC that merges four independent amplifiers within a single package.
- This IC provides high gain.
The disadvantages of LM348 IC include the following.
- The LM358/LM324 has a different output stage that is more prone to crossover distortion.
- Never leave op-amp inputs unconnected, because this leads to high-frequency oscillation that leads to overheating.
- This amplifier IC exhibits less supply-current drain, input bias current & offset currents that are much lower than µA741.
Applications
The applications of LM348 IC include the following.
- LM348 operational amplifiers are used to amplify different frequency-based signals.
- These can be utilized for circuits or devices as voltage sources.
- These can be utilized as comparators.
- This op-amp IC can be used within industrial applications.
- It is used in applications like megaphones, home entertainment systems, microphones, speakers, etc.
- This IC is used in many different applications like amplification, signal conditioning, oscillators, active filters, precision rectifiers, sensor signal processing, and voltage comparators,etc.
Please refer to this link for the LM348 IC Datasheet.
Thus, this is an overview of LM348 IC, pin-out, features, specifications, circuit, working, pros, cons, and its uses. The LM348 IC is an independent, quadruple, high-gain, and internally compensated op-amp that is designed to have similar operating characteristics to the μA741. This is a general-purpose operational amplifier with four internal in-built amplifiers. The LM348 IC provides an outstanding platform for designing preamplifier circuits. Its low noise characteristics, wide voltage supply range, and versatile functionalities will make this IC a perfect choice for enthusiasts and audio professionals. Thus, here is a question for you, what is LM258 IC?