Part # LM3914 datasheet

Part Manufacturer: National Semiconductor

National Semiconductor

Part Description: LM3914 Dot Bar Display Driver

Part Details:

LM3914 February 2003 Dot/Bar LM3914Dot/Bar Display DriverGeneral Description Much of the display flexibility derives from the fact that all Display outputs are individual, DC regulated currents. Various effects The LM3914 is a monolithic integrated circuit that senses can be achieved by modulating these currents. The indi- analog voltage levels and drives 10 LEDs, providing a linear vidual outputs can drive a transistor as well as a LED at the analog display. A single pin changes the display from a same time, so controller functions including "staging" control moving dot to a bar graph. Current drive to the LEDs is can be performed. The LM3914 can also act as a program- regulated and programmable, eliminating the need for resis- mer, or sequencer. Driver tors. This feature is one that allows operation of the whole The LM3914 is rated for operation from 0°C to +70°C. The system from less than 3V. LM3914N-1 is available in an 18-lead molded (N) package. The circuit contains its own adjustable reference and accu- The following typical application illustrates adjusting of the rate 10-step voltage divider. The low-bias-current input reference to a desired value, and proper grounding for ac- buffer accepts signals down to ground, or V-, yet needs no curate operation, and avoiding oscillations. protection against inputs of 35V above or below ground. Thebuffer drives 10 individual comparators referenced to theprecision divider. Indication non-linearity can thus be held Features typically to 1/2%, even over a wide temperature range. n Drives LEDs, LCDs or vacuum fluorescents Versatility was designed into the LM3914 so that controller, n Bar or dot display mode externally selectable by user visual alarm, and expanded scale functions are easily added n Expandable to displays of 100 steps on to the display system. The circuit can drive LEDs of many n Internal voltage reference from 1.2V to 12V colors, or low-current incandescent lamps. Many LM3914s n Operates with single supply of less than 3V can be "chained" to form displays of 20 to over 100 seg- n Inputs operate down to ground ments. Both ends of the voltage divider are externally avail- n Output current programmable from 2 mA to 30 mA able so that 2 drivers can be made into a zero-center meter. n No multiplex switching or interaction between outputs The LM3914 is very easy to apply as an analog meter circuit. n Input withstands ±35V without damage or false outputs A 1.2V full-scale meter requires only 1 resistor and a single3V to 15V supply in addition to the 10 display LEDs. If the 1 n LED driver outputs are current regulated, resistor is a pot, it becomes the LED brightness control. The open-collectors simplified block diagram illustrates this extremely simple n Outputs can interface with TTL or CMOS logic external circuitry.

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LM3914.pdf Datasheet