TSL2772

LIGHT-TO-DIGITAL CONVERTER

with PROXIMITY SENSING

TAOS131 − DECEMBER 2011

13

The LUMENOLOGY

r Company

r

r

Copyright

E 2011, TAOS Inc.

www.taosinc.com

Interrupts

The interrupt feature simplifies and improves system efficiency by eliminating the need to poll the sensor for

light intensity or proximity values outside of a user-defined range. While the interrupt function is always enabled

and it’s status is available in the status register (0x13), the output of the interrupt state can be enabled using

the proximity interrupt enable (PIEN) or ALS interrupt enable (AIEN) fields in the enable register (0x00).

Four 16-bit interrupt threshold registers allow the user to set limits below and above a desired light level and

proximity range. An interrupt can be generated when the ALS CH0 data (C0DATA) falls outside of the desired

light level range, as determined by the values in the ALS interrupt low threshold registers (AILTx) and ALS

interrupt high threshold registers (AIHTx). Likewise, an out-of-range proximity interrupt can be generated when

the proximity data (PDATA) falls below the proximity interrupt low threshold (PILTx) or exceeds the proximity

interrupt high threshold (PIHTx).

It is important to note that the thresholds are evaluated in sequence, first the low threshold, then the high

threshold. As a result, if the low threshold is set above the high threshold, the high threshold is ignored and only

the low threshold is evaluated.

To further control when an interrupt occurs, the device provides a persistence filter. The persistence filter allows

the user to specify the number of consecutive out-of-range ALS or proximity occurrences before an interrupt

is generated. The persistence filter register (0x0C) allows the user to set the ALS persistence filter (APERS)

and the proximity persistence filter (PPERS) values. See the persistence filter register for details on the

persistence filter values. Once the persistence filter generates an interrupt, it will continue until a special function

interrupt clear command is received (see command register).

Prox

ADC

Prox

Data

CH0

ADC

CH0

Data

Prox

Integration

CH0

CH1

Upper Limit

Upper Limit

Lower Limit

Lower Limit

Prox Persistence

PILTH(r09), PILTL(r08)

AIHTH(r07), AIHTL(r06)

ALS Persistence

AILTH(r05), AILTL(r04)

PIHTH(r0x0B), PIHTL(r0x0A)

PPERS(r0x0C, b7:4)

APERS(r0x0C, b3:0)

Figure 13. Programmable Interrupt