LM348N - Quad 741 Operational Amplifier

Overview

The LM348N is a quad operational amplifier (op-amp) that integrates four independent, high-gain, internally compensated, low-power amplifiers into a single package. Designed as a true quad version of the classic 741 op-amp, the LM348N provides identical functional characteristics while offering improved performance in terms of power consumption and input bias currents. This component is ideal for applications requiring multiple op-amps in a compact form factor, reducing board space and simplifying circuit design.

The LM348N is part of the LM148 series, which is optimized for low power consumption. The total supply current for all four amplifiers is comparable to that of a single 741 op-amp, making it an efficient choice for battery-powered and energy-sensitive applications. Additionally, the LM348N features excellent isolation between amplifiers due to independent biasing and advanced layout techniques that minimize thermal coupling.

Features

• Quad 741 Op-Amp: Four independent amplifiers in a single package, each functionally equivalent to the 741 op-amp.
• Low Power Consumption: Total supply current for all four amplifiers is comparable to a single 741 op-amp.
• Improved Input Characteristics: Lower input offset currents and input bias currents compared to standard 741 op-amps.
• High Isolation: Independent biasing and optimized layout minimize thermal coupling between amplifiers.
• Internally Compensated: No external compensation required for stable operation.
• Wide Supply Voltage Range: Operates from ±5V to ±18V, making it versatile for various applications.
• Robust Performance: High common-mode rejection ratio (CMRR) and power supply rejection ratio (PSRR).

Applications

The LM348N is widely used in applications requiring multiple op-amps with reliable performance and low power consumption. Common use cases include:

• Signal Conditioning: Filtering, amplification, and buffering in analog signal processing circuits.
• Instrumentation Amplifiers: Precision measurement systems requiring multiple amplification stages.
• Active Filters: Low-pass, high-pass, and band-pass filter designs.
• Analog Computation: Summing amplifiers, integrators, and differentiators.
• Audio Processing: Preamplifiers, tone control circuits, and mixing consoles.
• Power Supply Control: Voltage regulation and monitoring circuits.
• Industrial Control Systems: Sensor interfacing and feedback loop control.

Electrical Characteristics

The following table summarizes the key electrical specifications of the LM348N under typical operating conditions (unless otherwise noted):

• Supply Voltage Range: ±5V to ±18V
• Input Offset Voltage: 2 mV (max)
• Input Bias Current: 30 nA (max)
• Input Offset Current: 5 nA (max)
• Common-Mode Rejection Ratio (CMRR): 90 dB (typ)
• Power Supply Rejection Ratio (PSRR): 96 dB (typ)
• Open-Loop Gain: 100 V/mV (min)
• Bandwidth (Gain-Bandwidth Product): 1 MHz (typ)
• Slew Rate: 0.5 V/µs (typ)
• Total Supply Current (All Four Amplifiers): 3 mA (max)
• Operating Temperature Range: 0°C to +70°C

Package Information

The LM348N is available in a standard 14-pin dual in-line package (DIP), which is widely used in through-hole PCB designs. The package dimensions and pinout are as follows:

• Package Type: 14-Pin PDIP (Plastic Dual In-Line Package)
• Dimensions: 19.3 mm x 6.35 mm (0.76 in x 0.25 in)
• Pin Configuration:
  • Pin 1: Output A
  • Pin 2: Inverting Input A
  • Pin 3: Non-Inverting Input A
  • Pin 4: V- (Negative Supply)
  • Pin 5: Non-Inverting Input B
  • Pin 6: Inverting Input B
  • Pin 7: Output B
  • Pin 8: Output C
  • Pin 9: Inverting Input C
  • Pin 10: Non-Inverting Input C
  • Pin 11: V+ (Positive Supply)
  • Pin 12: Non-Inverting Input D
  • Pin 13: Inverting Input D
  • Pin 14: Output D

Conclusion

The LM348N is a versatile and efficient quad operational amplifier that combines the familiarity of the 741 op-amp with enhanced performance and power efficiency. Its low input bias currents, excellent isolation between amplifiers, and compact package make it an excellent choice for a wide range of analog circuit applications. Whether used in signal conditioning, active filtering, or industrial control systems, the LM348N delivers reliable performance while simplifying board layout and reducing component count.