LED current drive is regulated and programmable, eliminating the need for current limiting resistors. The IC contains an adjustable voltage reference and an accurate ten-step voltage divider.
VU meter uses just one IC and a very few number of external components. It displays the audio level in terms of 10 LEDs.
The LM3915 is a device that senses analog input voltage levels (in our case the audio line out) and drives ten LED’s proving a logarithmic 3 dB.