TSL2771

LIGHT-TO-DIGITAL CONVERTER

with PROXIMITY SENSING

TAOS100B − FEBRUARY 2011

13

The LUMENOLOGY

r Company

r

r

Copyright

E 2011, TAOS Inc.

www.taosinc.com

State Diagram

Figure 13 shows a more detailed flow for the state machine. The device starts in the sleep mode. The PON bit

is written to enable the device. A 2.72-ms delay will occur before entering the start state. If the PEN bit is set,

the state machine will step through the proximity states of proximity accumulate and then proximity ADC

conversion. As soon as the conversion is complete, the state machine will move to the following state.

If the WEN bit is set, the state machine will then cycle through the wait state. If the WLONG bit is set, the wait

cycles are extended by 12

step to the ALS state.

The AEN should always be set, even in proximity-only operation. In this case, a minimum of 1 integration time

step should be programmed. The ALS state machine will continue until it reaches the terminal count at which

point the data will be latched in the ALS register and the interrupt set, if enabled.

Prox

Check

PON = 1

PON = 0

Sleep

ALS

Check

Wait

Check

Start

Wait

WEN = 1

Prox

Accum

Prox

ADC

ALS

ALS

Delay

PEN = 1

AEN = 1

Up to 255 LED Pulses

Pulse Frequency: 62.5 kHz

Time: 16

ms − 4.2 ms

Maximum 4.2ms

Up to 256 steps

Step: 2.72 ms

Time: 2.72 ms − 696 ms

120 Hz Minimum − 8 ms

100 Hz Minimum − 10 ms

Counts up to 256 steps

Step: 2.72 ms

Time: 2.72 mS − 696 ms

Recommended − 2.72 ms 1024 Counts

WLONG = 0

Counts up to 256 steps

Step: 2.72 ms

Time: 2.72 ms − 696 ms

Minimum − 2.72 ms

WLONG = 1

Counts up to 256 steps

Step: 32.64 ms

Time: 32.64 ms − 8.35 s

Minimum − 32.64 ms

Time: 2.72 ms

Prox

Delay

2.72 ms

Figure 13. Expanded State Diagram