Scaling LED Output by the Flux Bin with the Luminus Lumen Calculator for Specialty Illumination SMD

The Luminus Lumen Calculator for Specialty Illumination SMD helps you determine how many LEDs are needed to achieve a specific target system flux (lumens). It uses a reference LED flux value from the datasheet for its calculations. However, the actual luminous flux of the LEDs you purchase may differ, so it's essential to understand how to scale the output based on your specific products.

In the provided calculation example of MP-3030-11F2, the input parameters are as follows: CCT 3000K, 80 CRI, a target drive current of 65 mA, and a case temperature of 25ºC. With a target system flux of 200 lm, the calculator determines that the minimum number of LEDs required is six, which results in a total system flux of 222 lm using the E2 reference flux bin.

 

1. Identify Your LED's Flux Bin

LEDs are sorted into "bins" based on their luminous flux output. This bin code is printed on the label of the packaging box and indicates the specific flux range for your batch of LEDs. The first part of the bin code relates to flux. For example, in the MP-3030-11F2 Datasheet (page 5), the flux bins are designated by a letter and number (e.g., D7, E1, E2), measured at a drive current of 65 mA and a case temperature of 25°C:
 

 

2. Scale System Output Based on Your Flux Bin

The Lumen Calculator bases its calculations on a reference bin, which for the MP-3030-11F2 is the E2 bin. The average flux for this bin (midpoint of the 36-38 lm range) is 37 lm.

The calculator's output can be scaled using a simple ratio.

Formula:

Your System Flux = (Calculator's System Flux) × (Average Flux of Your Bin / Average Flux of the Calculator's Bin)

Example: The calculator shows a system output of 222 lm using 6 LEDs, based on the E2 reference bin. If your LEDs are from the E3 bin (average flux of 39 lm), you can calculate your system's actual flux as follows:

  222 lm × 39 lm / 37 lm ​= 234 lm

By applying this calculation, you can determine that your system's actual output would be approximately 234 lm.

3. Understand Other System Parameters

The Luminus Lumen Calculator provides more than just the number of LEDs. It also gives you important electrical parameters for your system. Here’s a breakdown of how they are derived:

Average LED Voltage: The calculator provides the total system voltage. To find the average voltage per LED, simply divide the total voltage by the number of LEDs in the series. In the example, with a system voltage of 15.9 V and 6 LEDs, the average voltage per LED is:
   
   Average LED Voltage = 15.9 V / 6 = 2.7 V
   
Electric Power (Consumed): The total power consumed by the system is the product of the drive current and the total system voltage.
   
   Electric Power = Drive Current × System Voltage
   
   Electric Power = 0.065 A × 15.9 V = 1.034 W
   
Efficacy (lm/W): Efficacy is a measure of a lighting system's efficiency, calculated by dividing the total luminous flux (light output) by the total electric power consumed.
   
   Efficacy = Luminous Flux​ / Electric Power 
   
   Efficacy = 222 lm​ / 1.034 W = 214.8 lm/W

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