TCS3771

COLOR LIGHT-TO-DIGITAL CONVERTER

with PROXIMITY SENSING

TAOS110A − MARCH 2011

12

r

r

Copyright

E 2011, TAOS Inc.

The LUMENOLOGY

r Company

www.taosinc.com

LED On

LED Off

14

ms

IR LED Pulses

Subtract

Background

Add IR +

Background

Figure 11. Proximity IR LED Waveform

The proximity integration time (PTIME) is the period of time that the internal ADC converts the analog signal

to a digital count. It is recommend that this be set to a minimum of PTIME = 0xFF or 2.4 ms.

The combination of LED power and number of pulses can be used to control the distance at which the sensor

can detect proximity. Figure 12 shows an example of the distances covered with settings such that each curve

covers 2

Figure 12

PROXIMITY ADC COUNT

vs.

RELATIVE DISTANCE

Relative Distance

1

8

y

16

y

0

200

400

600

800

1000

100 mA,

64 Pulses

100 mA,

16 Pulses

100 mA,

4 Pulses

100 mA,

1 Pulse

25 mA,

1 Pulse