TMD4903 Datasheet, PDF (35/86 Pages) ams AG – Color and Proximity Sensor Module with mobeam

TMD4903 − Register Description
Figure 41:
Proximity Data Register
Field
PDATA
Register
0x9C
0x9D
Proximity Data Registers (0x9C – 0x9D)
Proximity data is stored as a 14-bit value (two bytes). PDATA has
a two-byte latch like 16-bit fields. Reading the low byte first
latches the high byte.
Proximity detection uses an Automatic Pulse Control (APC)
mechanism that adjusts the number of pulses per measurement
based on the magnitude of the reflected IR signal. As the
magnitude of the signal increases, the number of pulses
decreases. Proximity detection uses a 10-bit ADC that is
extended to a 14-bit dynamic range for PDATA using the
following formula:
PDATA = ADC_value x (16 / proximity pulses)
PDATA is the average response of the non-masked proximity
photodiodes. If one or more photodiodes are masked
(CFG2 register 0x9F), the proximity response will remain the
same since it is an average of the active photodiodes. PDATA is
therefore proportional to the reflected energy per pulse,
independent of the number of pulses used.
Bits
7:0
13:8
Description
Proximity data low byte
Proximity data high byte
ams Datasheet
[v1-12] 2015-May-14
Page 35
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