Designing a circuit with the LM3915 requires precise calculation of resistor values to set the desired reference voltage and LED current. An simplifies this process, ensuring accurate performance and preventing component damage.
: You can set the entire display's brightness and full-scale range (typically 1.2V to 12V) using just one or two external resistors. Versatile Power : It runs on anything from
You'd spend 10 minutes with a calculator and the datasheet, often realizing halfway through that you don't own the specific 1.24kΩ resistor the math suggests. lm3915 calculator updated
(12V−2V)×0.1A=1Wopen paren 12 V minus 2 V close paren cross 0.1 A equals 1 W This exceeds the package rating. Keep LED supply voltage ( VLEDcap V sub cap L cap E cap D end-sub ) as close to the LED forward voltage as possible ( is optimal). Always place a tantalum or electrolytic capacitor between Pin 2 (
One of the biggest challenges when designing with the LM3915 is selecting the correct resistors and capacitors to achieve accurate and reliable performance. The IC requires a specific ratio of resistors to set the reference voltage, gain, and LED current, which can be complex to calculate, especially for designers without extensive experience with the device. Designing a circuit with the LM3915 requires precise
One of the LM3915's most elegant features is that a single resistor ( Rset ) sets the current for all ten LEDs. This eliminates the need for individual current-limiting resistors for each LED.
ILED≈12.5R1cap I sub cap L cap E cap D end-sub is approximately equal to the fraction with numerator 12.5 and denominator cap R sub 1 end-fraction ILEDcap I sub cap L cap E cap D end-sub Versatile Power : It runs on anything from
, you establish a voltage divider that sets the full-scale low and high limits for the internal comparator string. The internal buffer amplifies or stabilizes this reference to drive the internal resistor ladder. The Core Equations
Designing with the LM3915 requires precise resistor calculations to set the reference voltage ( VREFcap V sub cap R cap E cap F end-sub ) and LED current ( ILEDcap I sub cap L cap E cap D end-sub