Lm3915 Calculator | Updated

$$R2 = R1 \times (\fracV_upper1.25 - 1)$$

You want a 10V range meter. You already calculated R1 as 1kΩ (for dimmer LEDs, ~1.25mA) for this example: lm3915 calculator updated

The LM3915 needs only two resistors, R₁ and R₂, to determine the LED current and the input signal scaling. A. LED Current Calculation ( ILEDcap I sub cap L cap E cap D end-sub $$R2 = R1 \times (\fracV_upper1

Use the formula $R2 = R1 \times (\fracV_upper1.25 - 1)$ and you will never go wrong. Happy building LED Current Calculation ( ILEDcap I sub cap

) to prevent burning out the IC, especially when driving all 10 LEDs in bar mode.

) and high LED current, the LM3915 can become hot. The IC dissipates the excess voltage dropped across its internal driver transistors. To lower IC temperature, use a separate, lower voltage power supply (e.g., 3.3V to 5V) for the LED anodes while powering the IC Pin 3 with the required operating voltage.

Older calculators never did that, leading to many melted chips.