TMD27711 Datasheet, PDF (9/33 Pages) List of Unclassifed Manufacturers – The technical content of this TAOS datasheet is still valid

TMD2771
DIGITAL ALS
and PROXIMITY MODULE
TAOS143B − SEPTEMBER 2012
PRINCIPLES OF OPERATION
System State Machine
The device provides control of ALS, proximity detection and power management functionality through an
internal state machine. After a power-on-reset, the device is in the sleep mode. As soon as the PON bit is set,
the device will move to the start state. It will then continue through the Prox, Wait, and ALS states. If these states
are enabled, the device will execute each function. If the PON bit is set to a 0, the state machine will continue
until all conversions are completed and then go into a low-power sleep mode.
lid ^Sleep
PON = 1 (r 0:b0)
PON = 0 (r 0:b0)
a _Start
v _Prox
ALS
ill Wait
G ^{t Figure 6. Simplified State Diagram}
s _{NOTE: In this document, the nomenclature uses the bit field name in italics followed by the register number and}
A ^t _{bit number to allow the user to easily identify the register and bit that controls the function. For example, the}
power on (PON) is in register 0, bit 0. This is represented as PON (r0:b0).
s _{en Photodiodes}
m ^{t Conventional silicon detectors respond strongly to infrared light, which the human eye does not see. This can}
lead to significant error when the infrared content of the ambient light is high (such as with incandescent lighting)
a ^{n due to the difference between the silicon detector response and the brightness perceived by the human eye.}
o This problem is overcome through the use of two photodiodes. The Channel 0 photodiode is sensitive to both
visible and infrared light, while the Channel 1 photodiode is sensitive primarily to infrared light. Two integrating
c _{ADCs convert the photodiode currents to digital outputs. The ADC digital outputs from the two channels are}
Technical ^{used in a formula to obtain a value that approximates the human eye response in units of lux.}
Copyright E 2012, TAOS Inc.
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