Pin of LM3915 robotic.icu

robotic.icu: Pin of LM3915
Posted in: Pinouts | by Brian Taylor | 2025 Nov 24


LM3915 -- More Picts - Open image

The LM3915 is a logarithmic dot/bar display driver IC with 18 pins, designed to drive 10 LEDs, LCDs, or vacuum fluorescent displays based on an analog input signal.

The IC operates with a high-impedance input buffer capable of accepting signals from 0V up to within 1.5V of the positive supply. The internal circuitry includes a 10-step voltage divider and 10 op-amp comparators, enabling a logarithmic 3 dB/step response. The output current for the LEDs is internally regulated and programmable, eliminating the need for external current-limiting resistors. The device is available in a 18-pin DIP package and is suitable for applications such as audio visualization, battery level indicators, and digital gauges.

Specification:
18 pins

The pinout is as follows:

Pin 1 and Pins 10 to 18: These pins are designated as LED1, LED2, ..., LED10, serving as the cathode connections for the 10 LEDs to be controlled. These outputs are sink-type, meaning the LEDs are connected between the positive supply and these pins.
Pin 2: V- / Ground, the ground pin of the IC.
Pin 3: V+ / Vcc, the positive supply voltage input, which can range from 3V to 25V.
Pin 4: RLO, the low-level voltage input for the external potential divider network used to set the full-scale voltage range.
Pin 5: Signal, the analog input signal pin where the varying voltage (e.g., audio signal) is applied to control the LED display.
Pin 6: RHI, the high-level voltage input for the external potential divider network used to set the full-scale voltage range.
Pin 7: REF OUT, the output reference voltage used for LED current limiting.
Pin 8: REF ADJ, the reference voltage adjustment pin used to fine-tune the reference voltage.
Pin 9: Mode, the mode selection pin; connecting it to V+ (pin 3) activates bar mode, while leaving it unconnected activates dot mode.

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