TSL2672

DIGITAL PROXIMITY DETECTOR

TAOS133 − MAY 2012

13

The LUMENOLOGY

r Company

r

r

Copyright

E 2012, TAOS Inc.

www.taosinc.com

System Timing

The system state machine shown in Figure 9 provides an overview of the states and state transitions that

provide system control of the device. This section highlights the programmable features, which affect the state

machine cycle time, and provides details to determine system level timing.

When the proximity detection feature is enabled (PEN), the state machine transitions through the Prox Init, Prox

Accum, Prox Wait, and Prox ADC states. The Prox Init and Prox Wait times are a fixed 2.73 ms, whereas the

Prox Accum time is determined by the number of proximity LED pulses (PPULSE) and the Prox ADC time is

determined by the integration time (PTIME). The formulas to determine the Prox Accum and Prox ADC times

are given in the associated boxes in Figure 12. If an interrupt is generated as a result of the proximity cycle, it

will be asserted at the end of the Prox ADC state and transition to the Sleep state if SAI is enabled.

When the power management feature is enabled (WEN), the state machine will transition in turn to the Wait

state. The wait time is determined by WLONG, which extends normal operation by 12

WTIME. The formula to determine the wait time is given in the box associated with the Wait state in Figure 13.

Prox

Wait

Sleep

Idle

Prox

Init

Prox

Accum

Wait

Prox

ADC

Prox

Time: 2.73 ms

PPULSE: 0 ~ 255 pulses

Time: 16.0

μs/pulse

Range: 0 ~ 4.1 ms

Time: 2.73 ms

PTIME: 1 ~ 256 steps

Time: 2.73 ms/step

Range: 2.73 ms ~ 699 ms

WEN

!PON

Note: PON, PEN, WEN, and SAI are fields in the Enable register (0x00).

!WEN

PEN

INT & SAI

WTIME: 1 ~ 256 steps

WLONG = 0

Time:

2.73 ms/step

Range:

2.73 ms ~ 699 ms

WLONG = 1

Time:

32.8 ms/step

Range:

32.8 ms ~ 8.39s

Figure 13. Detailed State Diagram