LM4558

The LM4558 is a dual operational amplifier integrated circuit designed for audio and general-purpose analog signal processing. It was originally produced by National Semiconductor and is now offered under Texas Instruments after the two companies’ semiconductor assets merged. The device houses two identical op-amps in a single 8-pin package and is commonly available in DIP-8 and SO-8 forms.

The standard pinout corresponds to a typical dual op-amp arrangement: each amplifier has an inverting and a non-inverting input, and there is a shared voltage supply across the package. The common configuration places one amplifier’s output at pin 1, the inverting input at pin 2, the non-inverting input at pin 3, the negative supply at pin 4, the non-inverting input of the second amplifier at pin 5, the inverting input of the second amplifier at pin 6, the second output at pin 7, and the positive supply at pin 8. This layout makes the LM4558 compatible with many standard op-amp circuits.

The LM4558 is known for low-noise performance and good fidelity, attributes that have made it popular in audio applications. It is commonly used in audio preamplifiers, mixers, tone-control circuits, active filters, and various signal-processing stages in both consumer electronics and professional gear. It typically operates on dual supplies from approximately ±5 V to ±15 V and can be used in single-supply arrangements with appropriate biasing, though performance is optimized for dual-supply operation. Variants such as the LM4558A exist, and the part remains widely used in hobbyist and commercial equipment due to its balance of performance and cost.