LM3915MWC National Semiconductor Corporation, LM3915MWC Datasheet

LM3915MWC

Manufacturer Part Number

LM3915MWC

Description

Dot/bar Display Driver

Manufacturer

National Semiconductor Corporation

Datasheet

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LM3915

Dot/Bar Display Driver

General 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 ana-

log 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 re-

sistors. 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

parators 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 inten-

sity 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.

35V. The input buffer drives 10 individual com-

DS005104

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.

Features

n 3 dB/step, 30 dB range

n Drives LEDs, LCDs, or vacuum fluorescents

n Bar or dot display mode externally selectable by user

n Expandable to displays of 90 dB

n Internal voltage reference from 1.2V to 12V

n Operates with single supply of 3V to 25V

n Inputs operate down to ground

n Output current programmable from 1 mA to 30 mA

n Input withstands

n Outputs are current regulated, open collectors

n Directly drives TTL or CMOS

n The internal 10-step divider is floating and can be

The LM3915 is rated for operation from 0˚C to +70˚C. The

LM3915N-1 is available in an 18-lead molded DIP package.

referenced to a wide range of voltages

35V without damage or false outputs

February 2001

www.national.com

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