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LM3914N-1 Driver CAD Models, Datasheet
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 can 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 ilustrates this extremely simple extermnal 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 “stagin
LM3914N-1 Connection Diagram
LM3914N-1 Block Diagram
Features
·Drives LEDs, LCDs or Vacuum Fluorescents
·Bar or Dot Display Mode Externally Selectableby 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 Logic
·The Internal 10-step Divider is Floating andcan be Referenced toa
Wide Range of Voltages
LM3914N-1 Typical Application
Datasheet
You can download the datasheet the link given below.