Dot/Bar Display Driver Hookup Guide

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Contributors: Jimb0
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Introduction

The LM3914 and LM3916 are a two ICs in a series of monolithic, analog-controlled LED drivers. With these chips, all it takes is a single, analog signal to drive a string of 10+ LEDs, which can be configured into either bar mode (where all LEDs below a certain point turn on) or dot mode (with only a single LED on at a time). Hook them up properly, and you can create all sorts of nifty multi-LED displays, like an audio-visualizing VU meter.

Example VU Meter - 4 IC's driving 40 LEDs

These two ICs are similar in pin-out and interface. They differ in how they map an analog signal to output LED. The LM3914 uses a linear output scale while the LM3916 uses a more logarithmic VU (volume unit) scale, which makes it well-suited to audio applications.

In this tutorial we’ll dig into the datasheet of these LED drivers to find out what makes them tick, and take a close look at the pinout of the 18-pin DIP chips. Finally, we’ll show a pair of example circuits that show a simple hookup and a more advanced, cascaded hookup.

Required Materials

If you want to follow along with this tutorial, here are the components we used to make our driver circuits:

Suggested Reading

Working with these ICs is fairly simple – no crazy microcontrollers or programming required! Here are a few basic electronics concepts you should be familiar with, before moving forward: