TCS3772

COLOR LIGHT-TO-DIGITAL CONVERTER

with PROXIMITY SENSING

TAOS145B − SEPTEMBER 2012

12

r

r

Copyright

E 2012, TAOS Inc.

The LUMENOLOGY

r Company

www.taosinc.com

Referring again to Figure 12, the reflected IR LED and the background energy is integrated during the LED On

time, then during the LED Off time, the integrated background energy is subtracted from the LED On time

energy, leaving the external IR LED energy to accumulate from pulse to pulse.

After the programmed number of proximity pulses have been generated, the proximity ADC converts and scales

the proximity measurement to a 16-bit value, then stores the result in two 8-bit proximity data (PDATAx)

registers. ADC scaling is controlled by the proximity ADC conversion time (PTIME) which is programmable from

1 to 256 2.4-ms time units. However, depending on the application, scaling the proximity data will equally scale

any accumulated noise. Therefore, in general, it is recommended to leave PTIME at the default value of one

2.4-ms ADC conversion time (0xFF).

Once the first proximity cycle has completed, the proximity valid (PVALID) bit in the Status register will be set

and remain set until the proximity detection function is disabled (PEN).

For additional information on using the proximity detection function behind glass and for optical system design

guidance, please see available TAOS application notes.