Lm3915 Calculator Guide

From Vref = 5V to RHI = 1.5V: Use voltage divider between pin 7 and ground, middle to pin 4. Choose Rtop = 10 kΩ, Rbottom = 4.285 kΩ (approx 4.3k).

For a desired max LED at ( V_\textin,peak = V_\textmax ): LM3915 Calculator

Then choose ( R_\textin1, R_\textin2 ) as a voltage divider. [ R_\textset = \frac12.5I_\textLED ] From Vref = 5V to RHI = 1

[ V_\textin,peak = \sqrt2 \times V_\textrms ] [ R_\textset = \frac12

| Parameter | Formula | Standard value example | |-----------|---------|------------------------| | ( R_\textset ) | 12.5 / I_LED | 620 Ω for 20 mA | | ( V_\textref ) | 1.25 × (1+R2/R1) | 5.0 V: R1=1.2k, R2=3.6k | | LED step voltage (n from 1 to 10) | ( V_\textRLO \times 10^(n-1)/10 ) (if RHI/RLO = 1:0 ratio) | Step 6: ×3.16 from step 1 | | Power (bar mode) | ( 10 \times V_\textLED \times I_\textLED ) | 10×2V×0.02A = 0.4W |