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LM3914 Dot/Bar Display Driver Overview [Video]

Author: Mia Date: 19 Apr 2021  189

lm3914 datasheet

LM3914 is a monolithic ic that senses analog voltage levels and drives 10 LEDs, providing a linear analog display. A single pin changes the display from a moving dot to a bar graph.

 

This is an overview of LM3914 dot/bar display driver, we will provide the information of its pinout, datasheet, parameter, and where & how to use this device and so much more.

Top 5 electronics Projects using LM3914-15 IC | lm3914 & lm3915 circuits


Catalog

LM3914 Description

LM3914 Pinout

LM3914 Features

LM3914 Parameter

LM3914 Equivalent

Where to use LM3914 IC

How to use LM3914 IC

LM3914 Circuit

LM3914 Package

LM3914 Application

Component Datasheet


LM3914 Description

The LM3914 is a monolithic integrated circuit that senses analog voltage levels and drives 10 LEDs, providing a linear analog display. A single pin changes the display from a moving dot to a bar graph. Current drive to the LEDs is regulated and programmable, eliminating the need for resistors. This feature is one that allows operation of the whole system from less than 3V.

 

The LM3914 is very easy to apply as an analog meter circuit. A 1.2V full-scale meter requires only 1 resistor and a single 3V to 15V supply in addition to the 10 display LEDs. If the 1 resistor is a pot, it becomes the LED brightness control. The simplified block diagram illustrates this extremely simple external circuitry.

 

When in the dot mode, there is a small amount of overlap or “fade” (about 1 mV) between segments. This assures that at no time will all LEDs be “OFF”, and thus any ambiguous display is avoided. Various novel displays are possible.

 

The LM3914 is rated for operation from 0°C to +70°C. The LM3914N-1 is available in an 18-lead PDIP (NFK) package.


LM3914 Pinout

LM3914 LM3914 Pinout
LM3914 LM3914 Pinout

 

Pin Number Pin Name Description
1 and 10 to 18 LED1, LED2, LED3.....LED10 The 10 LEDs which has to be controlled is connected to these pins
2 V- / Ground Ground pin of the IC
3 V+ / Vcc Supply Voltage (3-18)V
4 RLO Low level voltage for potential divider
5 Signal Analog signal Input pin based on which the LED is controlled.
6 RHI High Level voltage for potential divider
7 REF OUT Output Reference Voltage for LED current limiting
8 REF ADJ Adjust pin for voltage reference
9 Mode Select between Dot/Bar Mode

LM3914 Features

  • Analog Controlled LED Driver IC

  • Number of controllable LEDs: 10

  • Operating Voltage: 3V to 18V

  • Input Analog voltage range: 1.2V to 12V

  • LED sink current: 2mA to 30mA (programmable)

  • Both Dot/Bar mode available

  • Can be cascaded to control upto 100 LEDs

  • Available in 18-pin DIP, PLCC package

  • It can drive LCDs, LEDs otherwise vacuum fluorescents. The dot otherwise bot display mode can be selected by the user externally.

  • It can be expandable up to 100 displays.


LM3914 Parameter

Manufacturer: Texas Instruments
Series: -
Packaging: Tube
Part Status: Obsolete
Display Type: LED LCD Vacuum Fluorescent (VF)
Configuration: Dot/Bar Display
Interface: -
Digits or Characters: 10 Steps
Current - Supply: 6.1mA
Voltage - Supply: 3V ~ 20V
Operating Temperature: 0°C ~ 70°C
Mounting Type: Through Hole
Package / Case: 18-DIP (0.300" 7.62mm)
Supplier Device Package: 18-PDIP
Base Part Number: LM3914

LM3914 Equivalent

 

LM3914 Equivalent LED Driver: LM3916

 

Alternative LED Driver IC’s: CD4511, MAX7219, CD4054


Where to use LM3914 IC

The LM3914 is an analog controlled LED driver IC, which means that it can control (turn on or off) 10 LED lights using an analog input voltage. This integrated circuit eliminates the need for a microcontroller and programming, as well as the hardware required to control ten LEDs.

 

The analog input voltage can range from 3V to 18V, and the LED current can be controlled with a single resistor on pin 7. (Ref Out). The IC also has two operating modes: DOT mode and BAR mode, and up to 100 LEDs can be controlled by cascading multiple ICs. These ICs are commonly used in visual alarms and other metering/monitoring applications because the LEDs can be controlled without flickering and flawlessly with equal brightness.

 

So, if you're looking for an IC to power your bar LED lights or another 10-LED sequence, this IC might be of interest to you.


How to use LM3914 IC

The benefit of using LM3914 is that it requires little hardware and is simple to set up. Simply connect the 10 LEDs to the IC, set the reference voltages for the input voltage, and limit the current through the LED, and we're done. The circuit below is an example of an LM3914 application circuit.

Simply connect the V+ and V- to power the IC, and the analog signal voltage is connected to pin 5. In this case, we used 9V to power the IC and monitor an analogy voltage ranging from 0 to 5V. Always keep in mind that the voltage used to power the IC (in this case, 9V) should be at least 1.5V higher than the monitoring voltage (here 5V).

 

Because we are monitoring 0-5V here, we set the low reference voltage (pin 4) to 0V and the high reference voltage (pin 6) to 5V. As you may have noticed, we connected all ten LEDs directly to the IC without using any current limiting resistors. This is because the IC has an internal current limiter and the current value can be set using the pin VRO (pin 7). The current calculation formulas are given below, where I is the current flowing through each LED and RL is the resistor connected to pin 7.

  I = 12.5/RL

In the preceding example, we used a 470 ohm resistor as Rl, so the current through each LED will be around 25mA; you can change the value as needed. Also, the cathode of the LED is connected to the IC, while the anode is connected to +5V. This is due to the fact that the IC output pins can only sink current and not source it.

 

The integrated circuit (IC) can operate in two modes: dot mode and bar mode. In dot mode, the mode pin (pin 9) must be left floating; in this mode, based on the input voltage, only one LED will be turned on. In Bar mode, connect the mode pin (pin 9) to V+, and the LED will turn on and off sequentially based on the input voltage. Both the modes are shown in the gif file above.


LM3914 Circuit

The circuit diagram for IC LM3914 is shown below. The circuit can be constructed using both basic electrical and electronic components. The IC LM3914 is a critical component of this circuit. An alarm driving switch for over range can be connected to a bar type LM series LED driving display circuit in the following circuit. This circuit is suitable for bar displays.

IC LM3914 Based Alarm Driver CircuitLM3914 Based Alarm Driver Circuit

The circuit here employs a PNP transistor, denoted by Q1. This transistor can be connected between the LED positive and negative terminals, and the base terminal of the transistor is connected to the IC's pin-10 to drive the LED10. In series, an alarm unit is connected to the transistor's collector terminal.

 

Normally, Q1 transistor, LED10, and the alarm unit are all turned off; however, if LED10 is activated, it pulls Q1 transistor through resistor R2 and thus activates the alarm unit, indicating that the condition is out of range.

 

In the above circuit, an alarm unit generates an acoustic alarm sound using a piezo siren unit, otherwise a gated astable switch unit that continuously activates the LED brightness between high and low levels beneath the over-range state, or a combination of both. If desired, the unit can be switched to any of the LED displays, and the alarm will sound if that or any other high LED is energized.


LM3914 Package

LM3914 Package


LM3914 Application

  • Battery Meter for Robot

  • Monitoring of 12V Car Battery

  • Tester Circuit for Soil Moisture

  • Monitoring of Lead Acid Battery Charger

  • Charge Monitoring Circuit for Atmospheric

  • Kitchen Exhaust Fan for Controlling Temperature

  • Meter Circuit for Temperature

  • Digital gauges

  • Electronic displays

  • Low-cost monitor devices

  • Crude Battery level indicators

  • Fade bars


Component Datasheet

LM3914 Datasheet

 

Ordering & Quality

Photo Mfr. Part # Company Description Package PDF Qty Pricing
(USD)
LM3914N-1 LM3914N-1 Company:Texas Instruments Remark:LED Driver 18-PDIP Package:18-DIP (0.300"", 7.62mm)
DataSheet
In Stock:On Order
Inquiry
Price:
Call
Inquiry
LM3914N-1-NOPB LM3914N-1-NOPB Company:Texas Instruments Remark:IC DRVR DOT/BAR DISPLAY 18DIP Package:18-DIP (0.300", 7.62mm)
DataSheet
In Stock:On Order
Inquiry
Price:
Call
Inquiry

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