LM3914N-1 National Semiconductor, LM3914N-1 Datasheet

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LM3914N-1

Manufacturer Part Number
LM3914N-1
Description
IC, DOT/BAR DISPLAY DRIVER, DIP-18
Manufacturer
National Semiconductor
Datasheets

Specifications of LM3914N-1

Led Driver Application
Bar-Graph Meter, Expanded Scale Meter
No. Of Outputs
10
Output Current
30mA
Output Voltage
1.34V
Input Voltage
3V To 15V
Dimming Control Type
Analog
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant

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© 2000 National Semiconductor Corporation
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 mov-
ing 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 accu-
rate 10-step voltage divider. The low-bias-current input
buffer accepts signals down to ground, or V
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
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 seg-
ments. Both ends of the voltage divider are externally avail-
able 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 ex-
ternal 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 dis-
play is avoided. Various novel displays are possible.
1
2
%, even over a wide temperature range.
DS007970
, yet needs no
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 indi-
vidual outputs can drive a transistor as well as a LED at the
same time, so controller functions including “staging” control
can be performed. The LM3914 can also act as a program-
mer, 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 accu-
rate operation, and avoiding oscillations.
Features
n Drives LEDs, LCDs or vacuum fluorescents
n Bar or dot display mode externally selectable by user
n Expandable to displays of 100 steps
n Internal voltage reference from 1.2V to 12V
n Operates with single supply of less than 3V
n Inputs operate down to ground
n Output current programmable from 2 mA to 30 mA
n No multiplex switching or interaction between outputs
n Input withstands
n LED driver outputs are current regulated,
n Outputs can interface with TTL or CMOS logic
n The internal 10-step divider is floating and can be
open-collectors
referenced to a wide range of voltages
±
35V without damage or false outputs
January 2000
www.national.com

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LM3914N-1 Summary of contents

Page 1

... The LM3914 can also act as a program- mer, 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 accu- − ...

Page 2

Typical Applications Note: Grounding method is typical of all uses. The 2.2 µF tantalum or 10 µF aluminum electrolytic capacitor is needed if leads to the LED supply are 6" or longer. www.national.com Bar Graph Meter 2 ...

Page 3

... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Power Dissipation (Note 6) Molded DIP (N) Supply Voltage Voltage on Output Drivers Input Signal Overvoltage (Note 4) Divider Voltage Electrical Characteristics Parameter COMPARATOR Offset Voltage, Buffer and First ...

Page 4

Electrical Characteristics Note 2: Unless otherwise stated, all specifications apply with the following conditions REF RHI RLO + + − ...

Page 5

Typical Performance Characteristics Reference Adjust Pin Current vs Temperature DS007970-22 Input Current Beyond Signal Range (Pin 5) DS007970-25 Total Divider Resistance vs Temperature DS007970-28 (Continued) LED Current-Regulation Dropout DS007970-23 LED Current vs Reference Loading DS007970-26 Common-Mode Limits DS007970-29 5 LED ...

Page 6

Block Diagram (Showing Simplest Application) www.national.com 6 DS007970-3 ...

Page 7

Functional Description The simplifed LM3914 block diagram is to give the general idea of the circuit’s operation. A high input impedance buffer operates with signals from ground to 12V, and is protected against reverse and overvoltage signals. The signal is ...

Page 8

Mode Pin Functional Description (Continued) LED No the second device comes on. The connection for cascading in dot mode has already been described and is depicted below. As long as the input signal voltage is below the threshold ...

Page 9

Typical Applications Zero-Center Meter, 20-Segment 9 DS007970-7 www.national.com ...

Page 10

Typical Applications (Continued) * This application illustrates that the LED supply needs practically no filtering Calibration: With a precision meter between pins 4 and 6 adjust R1 for voltage V The adjustments are non-interacting. Application Example: Grading 5V Regulators Highest ...

Page 11

Typical Applications (Continued) LEDs light up as illustrated with the upper lit LED indicating the actual input voltage. The display appears to increase resolution and provides an analog indication of overrange. Indicator and Alarm, Full-Scale Changes Display from Dot to ...

Page 12

Typical Applications (Continued) Full-scale causes the full bar display to flash. If the junction of R1 and C1 is connected to a different LED cathode, the display will flash when that LED lights, and at any higher input signal. Hysteresis ...

Page 13

Typical Applications (Continued) Operating with a High Voltage Supply (Dot Mode Only) The LED currents are approximately 10 mA, and the LM3914 outputs operate in saturation for minimum dissipation. * This point is partially regulated and decreases in voltage with ...

Page 14

Typical Applications (Continued) * The exact wiring arrangement of this schematic shows the need for Mode Select (pin 9) to sense the V Programs LEDs Application Hints Three of the most commonly needed precautions for using the ...

Page 15

Application Hints (Continued) APPLICATION TIPS FOR THE LM3914 ADJUSTABLE REFERENCE GREATLY EXPANDED SCALE (BAR MODE ONLY) Placing the LM3914 internal resistor divider in parallel with a section ( 230 ) of a stable, low resistance divider greatly reduces voltage changes ...

Page 16

Application Hints (Continued) Non-Interacting Adjustments for Expanded Scale Meter (4.5V to 5V, Bar or Dot Mode) Adjusting Linearity of Several Stacked Dividers www.national.com Other Applications • “Slow” — fade bar or dot display (doubles resolution) • 20-step meter with single ...

Page 17

... Connection Diagrams Plastic Chip Carrier Package Top View Order Number LM3914V See NS Package Number V20A DS007970-18 Order Number LM3914N-1 See NS Package Number NA18A Order Number LM3914N See NS Package Number N18A * Discontinued, Life Time Buy date 12/20/99 17 Dual-in-Line Package DS007970-19 Top View * www ...

Page 18

... Reference JEDEC registration MS-001, Variation AC, dated May 1993. www.national.com inches (millimeters) unless otherwise noted Dual-In-Line Package (N) Order Number LM3914N-1 NS Package Number NA18A Plastic Chip Carrier Package (V) Order Number LM3914V NS Package Number V20A 18 ...

Page 19

... National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. inches (millimeters) unless otherwise noted (Continued) Dual-In-Line Package (N) Order Number LM3914N NS Package Number N18A * Discontinued, Life Time Buy date 12/20/99 2 ...

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