The AUDIOMETER chip is a one-chip LED bargraph driver for building audio meter displays. You can simply feed it an audio signal and a +5V supply and it does the rest. The application circuit is very straightforward. It also provides an optional ‘Peak Hold’ LED which shows the maximum level reached above the main display of instantaneous level.
It was intended to act as a replacement for the no-longer produced LM3914/LM3915/LM3916 series chips, but it is not identical to any of those, although it can easily be tweaked if that is your aim.
The datasheet includes the pinout diagram and application circuit.
For more details including the code and how to modify it, see the page about the audio meter project.