OB1203 Certification Preparation, Setup, and Test Procedure
X0119984 Rev.1.0
Mar 11, 2021
Page 12
Estimate the impact of the cover window of the DUT:
1. Remove the cover window from the DUT and apply it to the reference board prepared in the previous
section.
2. Apply black carbon tape on top of the cover window.
3. Start the DUT and let the ADC readout stabilize. In order to achieve better resolution, the LED current
automatically increases to a preset or until the crosstalk reaches 7000 ADC counts. Read the IR and red AC
counts (average the numbers displayed) and the LED currents in mA. Add the values in the following table.
4. To verify the influence of the black tape, repeat the measurement without cover window on the DUT by
applying the black tape directly onto the OB1203.
Black tape applied directly to OB1203:
Note ADC counts per mA red
Note ADC counts per mA IR
Black tape applied to cover window
Note ADC counts per mA red
Note ADC counts per mA IR
Next, enter the ADC and mA values of the DUT with cover glass in the header file
OB1203.h
, as cross_ir_adc,
cross_ir_mA, cross_r_adc, cross_r_mA. In the following example, the IR current was 170mA and the IR ADC
count 600. Compile and load the program.
#define cross_ir_adc 600
#define cross_ir_mA 170
#define cross_r_adc 400
#define cross_r_mA 127
This sets the crosstalk cancellation in the software.
If you want to repeat the procedure, set the cross_r_mA and cross_ir_mA value to zero.
When the crosstalk cancellation is set by following the above process, the ADC values become small and
comparable to the noise that causes some changes in the ADC counts.
