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LM3915 level bargraph

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.
The features of the LM3915 device are :
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

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.
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. LED brightness is easily controlled with a single pot.
The internal 10-step divider is floating and can be referenced to a wide range of voltages


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