LM3915N-1 DIP-18 (For LED Display) Code: 34186005

The LM3915N-1 is a monolithic integrated circuit that senses analog voltage levels and drives ten LEDs, LCDs, or vacuum fluorescent displays, producing a logarithmic 3 dB/step analog display. It is highly popular for DIY audio VU meters, signal level indicators, and visualizers.

Key Specifications & Features

• Display Range:Logarithmic 3 dB/step, spanning a 30 dB range.
• Display Modes:Externally selectable between dot (single moving light) and bar graph modes via a mode control pin.
• Operating Voltage:Wide single-supply range from 3V to 25V.
• Current-Regulated Outputs:LED drive current is programmable (1 mA to 30 mA), eliminating the need for external current-limiting resistors.
• Voltage Reference:Internal adjustable voltage reference from 1.2V to 12V.
• Input Protection:Can withstand input signals of ± 35V without causing damage or false outputs.
• Package/Temperature:Available in an 18-lead molded DIP package (PDIP) and operates from 0°C to +70°C.

How It Works

The IC features a high-impedance input buffer that accepts signals down to ground. This buffer drives 10 individual comparators connected to an accurate, floating 10-step voltage divider. Because it uses a logarithmic scale, it is ideally suited for human auditory perception, which scales logarithmically rather than linearly.