Linux/OPT3002: Computation of Illuminance from Irradiance

Tool/software: Linux

Hi,
I need some clarification regarding the light to digital sensor - OPT3002.
I am working on a project which is having 3 light sensors to measure the illuminance in lux.The 3 sensors are :ISL29125, VEML6040 and OPT3002.

I am taking readings from these sensors and comparing it with the HTC digital lux meter.The readings of ISL2912 and VEML6040 are almost equal to the lux meter reading. But the readings of OPT3002 is showing a deviation of more than 70%.

I computed the Lux value from irradiance from of OPT3002 using the following formula.
                                                       1W/cm2 = 6830000 lux.
(with LSB_size = 0x0B , conversion time = 100ms, Automatic Full-Scale Setting Mode - OFF )

Please find the attached csv file of sensor readings and a photograph of the PCB showing the positions of these 3 sensors. The readings were taken by turning on and off the flash light of the mobile phone. The readings were measured in a time interval of 1 second.

In the photograph,

U5 - ISL29125

U4 - OPT3002

U3 - VEML6040

I would like to know the reason of the deviation and whether there is any other method/formula is available to compute lux from irradiance.

Log_Data_05022019.xlsx

Thanks,
Seline