TSL27721 datasheet(23/56 Pages) AMSCO

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ams Datasheet

Page 23

[v1-00] 2016-Aug-26

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TSL2772 − Principles Of Operation

System State Machine Timing

The system state machine shown in Figure 21 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 24. 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× when asserted, and WTIME. The formula to determine

the wait time is given in the box associated with the Wait state

in Figure 26.

When the ALS feature is enabled (AEN), the state machine will

transition through the ALS Init and ALS ADC states. The ALS Init

state takes 2.73 ms, while the ALS ADC time is dependent on

the integration time (ATIME). The formula to determine ALS ADC

time is given in the associated box in Figure 26. If an interrupt

is generated as a result of the ALS cycle, it will be asserted at

the end of the ALS ADC state and transition to the Sleep state

if SAI is enabled.

TSL27721 Datasheet(PDF) 23 Page - ams AG