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 30mA

No Multiplex Switching or Interaction BetweenOutputs

Input Withstands +35V without Damage orFalse Outputs

LED Driver Outputs are Current Regulated,Open-collectors

Outputs can Interface with TTL or CMos LogicT

he Internal 10-step Divider is Floating andcan be Referenced to a Wide Range ofVoltages

DESCRIPTION:

The LM3914 is a monolithic integrated circuit thatsenses analog voltage levels and drives 10 LEDsproviding a linear analog display.A single pinchanges the display from a moving dot to a bargraph.Current drive to the LEDs is regulated andprogrammable, eliminating the need for resistors.This feature is one that allows operation of the wholesystem from less than 3V.The circuit contains its own adjustable reference andaccurate 10-step voltage divider. The low-bias-currentinput buffer accepts signals down to ground, or Vyet needs no protection against inputs of 35V aboveor below ground. The buffer drives 10 individualcomparators referenced to the precision dividerIndication non-linearity can thus be held typically to½%,even over a wide temperature range Versatility was designed into the LM3914 so thatcontroller, visual alarm, and expanded scale functionsare easily added on to the display system. The circuitcan drive LEDs of many colors, or low-currentincandescent lamps.Many LM3914scanbe“chained”to form displays of 20 to over 100segments. Both ends of the voltage divider areexternally available so that 2 drivers can be madeinto a zero-center meter.The LM3914 is very easy to apply as an analogmeter circuit. A 1.2V full-scale meter requires only 1resistor and a single 3V to 15V supply in addition tothe 10 display LEDs. lf the 1 resistor is a pot, itbecomes the LED brightness control. The simplifiedblock diagramillustrates this extremely simpleexternal circuitry.When in the dot mode, there is a small amount ofoverlap or“fade”(about 1 mV)between segmentsThis assures that at no time will all LEDs be“OFF”and thus any ambiguous display is avoided. Variousnovel displays are possible.