LM3915 Bar-Graph Display Driver – Datasheet

Introduction

The LM3915 IC is a precision bar-graph display driver designed to visually represent analog signals in a logarithmic scale. Unlike the LM3914, which provides a linear display, the LM3915 is specifically optimized for applications such as audio level indicators, VU meters, and sound pressure level displays, where human perception is more responsive to logarithmic changes in sound. The IC can directly drive up to 10 LEDs, LCDs, or vacuum fluorescent displays, making it an essential component for creating professional-grade audio metering systems.

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A key advantage of the LM3915 bar-graph display driver is its ability to provide a 3 dB per step logarithmic display, covering a dynamic range of 30 dB with 10 LEDs. For applications requiring a wider scale, multiple LM3915 ICs can be cascaded, extending the display up to 70 dB or more. The IC supports both dot mode and bar mode, allowing users to choose between a power-efficient single LED indication or a visually striking full bar-graph display. This versatility makes the LM3915 ideal for stereo VU meters, battery level monitors, audio equipment, and signal strength indicators.

LM3915 Bar-Graph Display Driver

The operating voltage range of the LM3915 is typically 3V to 25V, making it highly flexible for use in various electronic systems. It includes an internal voltage reference (1.2V to 12V adjustable) and built-in LED current regulators, which simplify design by eliminating the need for external resistors for current limiting. The programmable LED current ranges from 1 mA to 30 mA per LED, ensuring consistent brightness across the display regardless of supply voltage fluctuations.

Engineers and hobbyists value the LM3915 IC for its robustness, accuracy, and ease of integration into both DIY and professional projects. It is widely used in audio amplifiers, equalizers, recording studio equipment, and consumer electronics where a clear and responsive audio level display is required. With its low distortion, high input voltage tolerance, and reliable performance, the LM3915 continues to be one of the most trusted logarithmic display driver ICs in the electronics industry. Its ability to directly interface with TTL or CMOS logic further enhances its versatility, making it a go-to choice for innovative electronic display solutions.

LM3915 Pinout

Key Features of LM3915 Bar-Graph Display Driver

• 3 dB/step, 30 dB Range
• Drives LEDs, LCDs, or Vacuum Fluorescents Bar or Dot Display Mode Externally Selectable by User
• Expandable to Displays of 90 dB
• Internal Voltage Reference from 1.2V to 12V Operates with Single Supply of 3V to 25V Inputs Operate Down to Ground
• Output Current Programmable from 1 mA to 30 MA
• Input Withstands ±35V without Damage or False Outputs
• Outputs are Current Regulated, Open Collectors
• Directly Drives TTL or CMOS
• The Internal 10-step Divider is Floating and can be Referenced to a Wide Range of
• Voltages
• The LM3915 is Rated for Operation from 0°C to +70°C. The LM3915N-1 is Available in an 18- lead PDIP Package.

LM3915 Specifications/Characteristics

LM3915 Bar-Graph Display Driver Pinout

More Circuit Layouts

Key Applications of LM3915

• Audio level indicators (VU meters) – logarithmic response for accurate sound-level monitoring
• Power meters for audio amplifiers – visualizing amplifier output power in dB scale
• Sound pressure level (SPL) meters – measuring loudness in professional audio setups
• Stereo system level displays – providing left/right channel indication in Hi-Fi systems
• Signal strength indicators – monitoring RF or audio signals with logarithmic scaling
• Battery level monitors – showing charge levels with logarithmic accuracy
• LED bar-graph meters – general-purpose display for voltages and signals in dB format
• DIY audio projects – simple implementation of logarithmic display circuits
• Portable audio devices – low-power consumption with dot mode display
• Laboratory and test instruments – visual representation of decibel-scaled measurements

Equivalent Driver ICs of LM3915

LM3916

Datasheet of LM3915 Bar-Graph Display Driver

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