TSL2672(2016) View Datasheet(PDF) - austriamicrosystems AG
Part Name
Description
MFG CO.
TSL2672 Datasheet PDF : 46 Pages
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TSL2672 − Principles Of Operation
on the number of proximity pulses, keep in mind that the signal
increases proportionally to PPULSE, while noise increases by
the square root of PPULSE.
Figure 21:
Proximity LED Current Driver Waveform
Reflected IR LED + Background
Background Energy Energy
LED On
LED Off
7.3 ms
16.0 ms
IR LED Pulses
ams Datasheet
[v1-00] 2016-Mar-23
Figure 20 illustrates light rays emitting from an external IR LED,
reflecting off an object, and being absorbed by the CH0 and
CH1 photodiodes. The proximity diode selector (PDIODE)
determines which of the two photodiodes is used for a given
proximity measurement. Note that neither photodiode is
selected when the device first powers up, so PDIODE must be
set for proximity detection to work.
Referring again to Figure 21, the reflected IR LED and the
background energy is integrated during the LED ON time, then
during the LED OFF time, the integrated background energy is
subtracted from the LED ON time energy, leaving the external
IR LED energy to accumulate from pulse to pulse. The proximity
gain (PGAIN) determines the integration rate, which can be
programmed to 1×, 2×, 4×, or 8× gain. At power up, PGAIN
defaults to 1× gain, which is recommended for most
applications. For reference, PGAIN equal to 8× is comparable to
the TSL2771 1× gain setting. During LED On time integration,
the proximity saturation bit in the Status register (0x13) will be
set if the integrator saturates. This condition can occur if the
proximity gain is set too high for the lighting conditions, such
as in the presence of bright sunlight. Once asserted, PSAT will
remain set until a special function proximity interrupt clear
command is received from the host (see Command Register).
After the programmed number of proximity pulses have been
generated, the proximity ADC converts and scales the proximity
measurement to a 16-bit value, then stores the result in two
Page 17
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