The following circuit diagram shows the logarithmic LED bar display using a device driver, the AN6884 IC. This IC accepts wide range of supply voltage ranging from 3.5V to 16V. The output current for each LED is in the constant value of 15mA, which is suitable for most LED types.
A current limiting resistor R should be inserted between Vcc and the LED anodes in order to operate at voltage higher than 6V. The table above shown the values needs to be chosen for appropriate maximum operating temperature and power supply voltage. The schematic is suitable to monitor the audio level of amplifier. [Panasonic Application Notes]