LM3915-DIP-18

The LM3915 is a monolithic IC that senses and converts analog voltage signals to digital quantities for driving ten LEDs, LCDs, or vacuum fluorescent displays. It provides a 3 dB-per-step analog display and can be configured for dot or bar display mode via the mode pin. LED drive current is adjustable through external settings, reducing the need for current-limiting resistors. The entire display system can be powered from a single supply of 3 V to 25 V. The device internally contains an adjustable voltage reference and a precision 10-step voltage divider. The input signal is fed to internal comparators through a high-impedance buffer, with an input signal range of 0 V to Vcc − 1.5 V. In addition, its input overvoltage protection capability extends to ±35 V. The input buffer drives ten independent comparators connected to a precision reference voltage divider. The LM3915's 3 dB-per-step display is suited for wide dynamic range signals such as audio levels, power supply voltages, light intensity, or vibration. Audio applications include average or peak level indication, power measurement, and RF signal strength measurement. Compared to conventional meters, linear displays using LEDs offer faster response and more reliable readings. LM3915 applications are straightforward — a full-scale 1.2 V meter requires only one resistor and ten LEDs. With an external potentiometer, a reference voltage from 1.2 V to 12 V independent of supply voltage can be obtained, and LED brightness is easily controlled. The LM3915 supports a wide range of applications, including driving LCDs, vacuum fluorescent displays, incandescent lamps, and multi-color LEDs. Multiple LM3915 devices can be cascaded to form dot or bar displays with a range of 60 dB or 90 dB. The LM3915 can also be cascaded with the LM3914 for linear or logarithmic displays, or with the LM3916 for wide-range VU meters. Operating temperature range: 0°C to 70°C; package: DIP18.

Key features

• Fast-response electronic VU meter
• Capable of driving LED, LCD, and vacuum fluorescent displays
• Dot/bar display mode switchable via external control
• Display range expandable to 90 dB
• Internal reference voltage range: 1.2 V ~ 12 V
• Output drive voltage requirement: 3 V ~ 25 V
• Adjustable output current range: 1 mA ~ 30 mA
• Input withstands ±35 V without damage or false output
• Adjustable output current, open-collector outputs
• Direct drive capability for TTL or CMOS logic
• Internal 10-step voltage divider with floating terminals for wide adjustment range