LM3914 Pinout, Datasheet, Replacement, Working and Uses

The LM3914 is a popular integrated circuit designed to drive LED displays in a variety of electronic applications. It simplifies the process of creating visual voltage level indicators by converting analog input signals into a corresponding LED display. This makes it an essential component in devices that require clear and accurate voltage representation, such as battery chargers, audio equipment, and power supply monitors.

The importance of the LM3914 in electronics lies in its versatility and ease of use. It provides a straightforward solution for creating bar graphs or dot displays, allowing for easy visualization of voltage levels. Its ability to operate in both bar and dot modes enhances its flexibility, making it suitable for a wide range of applications. Moreover, the LM3914's robust design and reliable performance have made it a staple in the toolkit of engineers and hobbyists alike, ensuring precise and dependable voltage level indication across numerous electronic projects. In this article, we'll delve into the LM3914 IC, exploring its pinout, circuit, uses, datasheet, replacement, and more details.

What is LM3914?

The LM3914, a monolithic integrated circuit (IC), functions to detect analog voltage levels and operate up to 10 LEDs, enabling the creation of a linear analog display. It offers the flexibility of displaying in either dot mode, illuminating one LED at a time, or bar mode, activating LEDs below a specific threshold. Switching between dot and bar modes is seamless, facilitated by a single pin. Moreover, the LM3914 regulates and customizes LED current drive, removing the necessity for resistors.

Efficiency characterizes the LM3914, boasting low power consumption with a typical standby supply current of 1.6mA (maximum 2.5mA) when all LEDs are inactive. Its versatility extends to various applications, from crafting audio-visual VU meters to representing diverse data using additional components or circuitry.

LM3914 Pinout

LM3914 has both 20-pin PLCC and 18-pin PDIP packages.

Pin Configuration of 20-pin PLCC

Pin Number	Pin Name	Description
1	LED1	LED Driver Output 1
2	V+	Supply Voltage
3	V-	Ground
4	Divider (Low End)	Low Reference Voltage Input
5	Signal Input	Signal Input
6	Divider (High End)	High Reference Voltage Input
7	NC	Not Connected
8	Reference Output	Reference Voltage Output
9	NC	Not Connected
10	Ref Adj	Reference Voltage Adjust
11	Mode Select	Selects Dot or Bar Mode
12	LED10	LED Driver Output 10
13	LED9	LED Driver Output 9
14	LED8	LED Driver Output 8
15	LED7	LED Driver Output 7
16	LED6	LED Driver Output 6
17	LED5	LED Driver Output 5
18	LED4	LED Driver Output 4
19	LED3	LED Driver Output 3
20	LED2	LED Driver Output 2

Pin Configuration of 18-pin PDIP

 

Pin Number	Pin Name	Description
1	LED1	LED Driver Output 1
2	V+	Supply Voltage
3	V-	Ground
4	Divider (Low End)	Low Reference Voltage Input
5	Signal Input	Signal Input
6	Divider (High End)	High Reference Voltage Input
7	Reference Output	Reference Voltage Output
8	Reference Adjust	Reference Voltage Adjust
9	Mode Select	Selects Dot or Bar Mode
10	LED10	LED Driver Output 10
11	LED9	LED Driver Output 9
12	LED8	LED Driver Output 8
13	LED7	LED Driver Output 7
14	LED6	LED Driver Output 6
15	LED5	LED Driver Output 5
16	LED4	LED Driver Output 4
17	LED3	LED Driver Output 3
18	LED2	LED Driver Output 2

Specifications and Features

• This IC can display the output in both bar and dot modes.

• The voltage reference can be adjusted using this circuit.

• Switching between dot and bar modes is possible with this circuit.

• It has a programmable LED sink current ranging from 2mA to 30mA.

• This integrated circuit is available in an 18-pin DIP PLCC package.

• The IC can control up to 10 LEDs.

• The LM3914 IC can be configured to drive up to 100 LED displays.

• The IC operates with a low-level voltage of 3V to 18V.

LM3914 Block Diagram

LM3914 Replacement

The LM3916 is a comparable integrated circuit to the LM3914. However, the LM3914 offers a range of alternatives, such as the CD4511, MAX7219, and CD4054, providing additional options for various applications.

How Does the LM3914 Work?

The LM3914 IC can control the illumination of 10 LED light bulbs, which is why it is recognized as an analog-controlled LED driver. The analog input voltage determines the activation of these ten LEDs.

Using the LM3914 IC minimizes the need for extensive programming and microcontrollers. Additionally, the number of electronic components required to manage the 10 LEDs is minimal. The analog voltage levels for this IC range from 3V to a maximum of 18V. LED current control is achieved by placing a single resistor on pin 7.

A notable feature of the LM3914 circuit is its dual display capability, allowing operation in either bar or dot display modes. With brightness control for the bar LED lights, this circuit is ideal for visual alarm or monitoring applications. Furthermore, multiple ICs can be used together to manage up to 100 LED light bulbs.

How to use LM3914?

To effectively use the LM3914 IC, begin by carefully connecting the 10 LEDs to the IC. Adjust the reference voltages of the input signal and control the current flowing through the LEDs. Power the display circuit using pins 2 and 3, and route the output analog signal voltage to pin 5.

For proper circuit operation, ensure the single supply voltage is at least 1.5V higher than the 5V monitoring voltage. Given that the monitoring voltage ranges from 0V to 5V, set pin 4 to 0V and pin 6 to 5V.

Connect all ten LEDs without any current limiting resistor, as the IC includes an internal current limiter set via pin 7. Connect the cathode of each LED to the circuit and the anode directly to the +5V since the IC's output pins can sink but not source current.

The LM3914 IC supports two modes of operation. In bar mode, connect pin 9 to pin 3; the input voltage will determine whether the LEDs turn on or off. In dot mode, leave pin nine open, allowing the LEDs to turn on based on the applied input voltage.

LM3914 Application

Battery Level Indicators

The LM3914 is widely used in battery level indicators, visually displaying the charge level through a series of LEDs, providing a clear and immediate indication of battery status.

Audio Level Meters

In audio applications, the LM3914 can be used to create visual, audio level meters, showing the volume level through a bar or dot display, aiding in audio equipment tuning and monitoring.

Power Supply Monitors

The LM3914 is ideal for power supply monitors, displaying voltage levels and ensuring that power supplies are operating within desired ranges.

Automotive Gauges

In automotive applications, the LM3914 can be used in gauges to display fuel levels, temperature readings, and other analog measurements, providing drivers with essential information at a glance.

Advantages and Disadvantages

LM3914 Advantages:

• Simple to use with minimal external components.

• Adjustable reference voltage and LED current for flexible design.

• Single-supply operation simplifies circuit requirements.

• Accurate and stable voltage measurement and display.

LM3914 Disadvantages:

• Limited to driving 10 LEDs per IC.

• Linear display may not be suitable for all applications requiring logarithmic or VU scale.

LM3914 Package

LM3914 Manufacturer

The LM3914 is manufactured by Texas Instruments, a leading provider of semiconductor products known for their high quality and reliability. Texas Instruments offers comprehensive support and documentation for the LM3914, ensuring ease of use and integration into electronic designs.

LM3914 Datasheet

Download LM3914 Datasheet PDF.

LM3914 vs. LM3915

Comparison of Features and Specifications

• LM3914: Linear display of input voltage, adjustable reference voltage, drives 10 LEDs.

• LM3915: Logarithmic display of input voltage, suitable for audio applications, drives 10 LEDs.

Differences in Performance and Functionality

The LM3914 offers a linear display, making it suitable for applications requiring a direct representation of input voltage. In contrast, the LM3915 provides a logarithmic display, ideal for audio level meters and applications needing a non-linear representation.

Suitability for Different Applications

The LM3914 is ideal for battery level indicators, power supply monitors, and general-purpose analog displays. The LM3915 is better suited for audio applications and any design requiring logarithmic scaling.

Conclusion

The LM3914 is a versatile and widely used integrated circuit that excels in voltage level indication and LED display driving. The LM3914's importance in various applications cannot be overstated. Its ability to provide accurate and visually intuitive voltage level displays makes it invaluable in battery level indicators, power supply monitoring, and audio equipment. Its flexibility in both bar and dot modes, along with easy cascading for extended range, makes it a preferred choice for many electronic projects. Whether used in simple DIY projects or complex industrial systems, the LM3914 continues to be a reliable and efficient solution for LED display driving and voltage indication needs.

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