LM3915N-1 Datasheet, PDF (1/31 Pages) Texas Instruments – LM3915 Dot/Bar Display Driver

LM3915
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SNVS740C – JANUARY 2000 – REVISED MARCH 2013
LM3915 Dot/Bar Display Driver
Check for Samples: LM3915
FEATURES
1
•2 3 dB/step, 30 dB Range
• Drives LEDs, LCDs, or Vacuum Fluorescents
• Bar or Dot Display Mode Externally Selectable
by User
• Expandable to Displays of 90 dB
• Internal Voltage Reference from 1.2V to 12V
• Operates with Single Supply of 3V to 25V
• Inputs Operate Down to Ground
• Output Current Programmable from 1 mA to 30
mA
• Input Withstands ±35V without Damage or
False Outputs
• Outputs are Current Regulated, Open
Collectors
• Directly Drives TTL or CMOS
• The Internal 10-step Divider is Floating and
can be Referenced to a Wide Range of
Voltages
The LM3915 is Rated for Operation from 0°C to
+70°C. The LM3915N-1 is Available in an 18-
lead PDIP Package.
DESCRIPTION
The LM3915 is a monolithic integrated circuit that
senses analog voltage levels and drives ten LEDs,
LCDs or vacuum fluorescent displays, providing a
logarithmic 3 dB/step analog display. One pin
changes the display from a bar graph to a moving dot
display. LED current drive is regulated and
programmable, eliminating the need for current
limiting resistors. The whole display system can
operate from a single supply as low as 3V or as high
as 25V.
The IC contains an adjustable voltage reference and
an accurate ten-step voltage divider. The high-
impedance input buffer accepts signals down to
ground and up to within 1.5V of the positive supply.
Further, it needs no protection against inputs of ±35V.
The input buffer drives 10 individual comparators
referenced to the precision divider. Accuracy is
typically better than 1 dB.
The LM3915's 3 dB/step display is suited for signals
with wide dynamic range, such as audio level, power,
light intensity or vibration. Audio applications include
average or peak level indicators, power meters and
RF signal strength meters. Replacing conventional
meters with an LED bar graph results in a faster
responding, more rugged display with high visibility
that retains the ease of interpretation of an analog
display.
The LM3915 is extremely easy to apply. A 1.2V full-
scale meter requires only one resistor in addition to
the ten LEDs. One more resistor programs the full-
scale anywhere from 1.2V to 12V independent of
supply voltage. LED brightness is easily controlled
with a single pot.
The LM3915 is very versatile. The outputs can drive
LCDs, vacuum fluorescents and incandescent bulbs
as well as LEDs of any color. Multiple devices can be
cascaded for a dot or bar mode display with a range
of 60 or 90 dB. LM3915s can also be cascaded with
LM3914s for a linear/log display or with LM3916s for
an extended-range VU meter.
1
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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