LM3914| Datasheet
Datasheet preview, take a look at Datasheets before downloading (Data Sheet is available on manufacturer site)
LM3914 Dot/Bar Display Driver
February 2003
LM3914 Dot/Bar Display Driver
General 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 circuit contains its own adjustable reference and accurate 10-step voltage divider. The low-bias-current input buffer accepts signals down to ground, or V-, yet needs no protection against inputs of 35V above or below ground. The buffer drives 10 individual comparators referenced to the precision divider. Indication non-linearity can thus be held typically to 1/2%, even over a wide temperature range. Versatility was designed into the LM3914 so that controller, visual alarm, and expanded scale functions are easily added on to the display system. The circuit can drive LEDs of many colors, or low-current incandescent lamps. Many LM3914s c
an be "chained" to form displays of 20 to over 100 segments. Both ends of the voltage divider are externally available so that 2 drivers can be made into a zero-center meter. 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. Much of the display flexibility derives from the fact that all outputs are individual, DC regulated currents. Various effects can be achieved by modulating these currents. The individual outputs can drive a transistor as well as a LED at the same time, so controller functions including "sta
ging" control can be performed. The LM3914 can also act as a programmer, or sequencer. The LM3914 is rated for operation from 0 C to +70 C. The LM3914N-1 is available in an 18-lead molded (N) package. The following typical application illustrates adjusting of the reference to a desired value, and proper grounding for accurate operation, and avoiding oscillations.
Features
Drives LEDs, LCDs or vacuum fluorescents Bar or dot display mode externally selectable by user Expandable to displays of 100 steps Internal voltage reference from 1.2V to 12V Operates with single supply of less than 3V Inputs operate down to ground Output current programmable from 2 mA to 30 mA No multiplex switching or interaction between outputs Input withstands 35V without damage or false outputs LED driver outputs are current regulated, open-collectors n Outputs can interface with TTL or CMOS logic n The internal 10-step divider is floating and can be referenced to a wide range of voltages n n n n n n n n n n
2004 National Semiconductor Corporation
DS007970
LM3914 Datasheet national Download PDF
Add this permalink to your bookmarks for future download of LM3914 datasheet
Permalink: http://datasheet.emcelettronica.com/national/LM3914
Comments
This project shows how to control the speed of a Panaflo L1A radiator fan and at the same time have a visual indication of the applied fan voltage. Only 6 of the 10 LED outputs of the LM3914 have been used as, that way, the display is 7 to 12V (1V / LED).
The entire circuitry, schematics and PCB layout are given at http://www.turbokeu.com/myprojects/fanregvoltmon.htm
This circuit is a simple, low cost and highly effective battery test meter. At the heart is the LM3914 IC. There is a 10 level LED visual checking system. This gives a pretty good level of accuracy. The circuit needs its own 12 V power supply in order to function accurately. Cells of various voltages can be checked using this circuit.
SOURCE: http://www.elecfree.com/electronic/circuit-test-battery-by-lm3914/
Using this circuit, you can do an elementary dot-bar display altrenation . The LED s are numbered 1 through 10. The display is controlled by a switch S1. Input is given to pin 5 of the IC.
SOURCE: http://www.elecfree.com/electronic/circuit-basic-dot-bar-display-for-lm3...
SOURCE2:http://www.national.com/mpf/LM/LM3914.html
The LM3914's use in this application is rather novel. Originally intended for high-visibility LED bargraph readouts, here the LM3914 is used as the basis of a 10-step variable brightness current-regulated white LED torch. The circuit can be built directly on the pins of the LM3914 to produce a package not much bigger than the LM3914 itself.
See more on http://www.siliconchip.com.au/cms/A_103805/article.html
This LED temperature thermometer project will display the room temperature where it is placed using 10 LEDs, with each LED representing 2 degree Fahrenheit step, forming a bargraph display. The LM3914 senses analog voltage levels and drives 10 LEDs, providing a linear analog display. Current drive to the LEDs is regulated and programmable, eliminating the need for resistors. This is a good project for beginners to electronics.
SOURCE:http://www.electronics-project-design.com/TemperatureThermometer.html
http://www.scribd.com/doc/3390651/electronic-thermometer-project-by-LM39...
http://www.scribd.com/doc/3390650/electronic-thermometer-project-by-LM39...